CN109781512B - Shearing resistance test device and method for reinforcing steel bar welding mesh welding spot - Google Patents
Shearing resistance test device and method for reinforcing steel bar welding mesh welding spot Download PDFInfo
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Abstract
The invention discloses a steel bar welding net welding spot shearing resistance test device and a method thereof, wherein the device comprises a steel hook for placing transverse steel bars of a shearing resistance sample, an upper chuck of a shearing resistance tester for clamping the top ends of the steel hook, and a lower chuck for clamping the bottom ends of two parallel vertical steel bars of the shearing resistance sample, a first horizontal U-shaped notch for accommodating the vertical steel bars is arranged at the hook body of the steel hook for accommodating the transverse steel bars, and the clamping part of the steel hook is hinged with a body part; the hook body of the transverse steel bar is a concave arc surface, an arc sliding block matched with the arc surface is in sliding fit on the arc surface, the top surface of the arc sliding block is an arc groove for placing the transverse steel bar, and a second horizontal U-shaped notch for accommodating the parallel steel bar is formed in the arc sliding block. The device is used for carrying out a steel bar welding net rib welding spot shearing resistance test, the welding spot is not damaged, the vertical stress steel bar rib welding can be detected, and the accuracy of the detection result is high.
Description
Technical Field
The invention relates to the technical field of shear resistance test of welding spots of reinforcing steel bars in the processing of reinforcing steel bar welding nets, in particular to a shear resistance test device and a shear resistance test method of welding spots of reinforcing steel bars in the processing of reinforcing steel bar welding nets.
Background
In the construction reinforcing steel bar processing technology, vertical reinforcing steel bars or longitudinal reinforcing steel bars and transverse reinforcing steel bars with the same or different diameters are vertically arranged at preset lengths and intervals respectively, and all crossing points are welded together by resistance spot welding in special reinforcing steel bar welding net processing equipment to form a planar net-shaped reinforcing steel bar, namely a reinforcing steel bar welding net. Generally, the transverse steel bars are non-stressed steel bars, generally one or a single transverse steel bar, and the vertical steel bars are stressed steel bars, and conventionally, the transverse steel bars are single transverse steel bars, and two parallel vertical steel bars, which are simply called parallel bars, are generated in recent years.
According to the national standard GB/T1499.3, section 3 of reinforcing steel bar for reinforced concrete and the technical specification of reinforced welding net concrete structure of industry standard JGJ114-2014, the finished product of the reinforced welding net can be normally put into use only after the shearing resistance test of the crossed welding spots is required.
In the prior art, a cross-shaped shear resistant test sample is generally cut out from a finished steel bar welding net, transverse steel bars in the cross-shaped shear resistant test sample are placed on a steel hook of the test device, namely, the transverse steel bars in the cross-shaped shear resistant test sample are placed on a steel hook of the test device, a horizontal U-shaped notch for accommodating vertical steel bars is formed in a hook body of the steel hook, the upper end of a straight rod of the steel hook is used for being clamped in an upper clamping head of a shear resistant test machine in the prior art, and the lower end of the vertical steel bars in the cross-shaped shear resistant test sample is used for being clamped in a lower clamping head of the shear resistant test machine in the prior art. The testing machine is started, and the lower clamping head of the testing machine moves downwards in a straight line, namely, is pulled and blocked by the transverse reinforcing steel bars, so that the welding point is subjected to shearing force. When the shearing force is greater than or equal to 0.3 times the yield force specified by the tensile vertical steel bar and can be understood as a shearing resistance value, the cross-shaped shearing resistance sample can be judged to be qualified, and the yield force specified by the tensile vertical steel bar is the product of the yield strength specified by the steel bar and the sectional area of the steel bar.
However, in practice, the welding spot shearing resistance test device for the steel bar welding net in the prior art is only suitable for a single vertical stressed steel bar, but cannot be applied to a shearing resistance test for two parallel vertical steel bars, namely a welding spot of a parallel steel bar, of the steel bar welding net. The main problems are: 1. according to the national standard and the industry standard, when the parallel reinforcement is subjected to a shearing resistance test, one of the two parallel vertical reinforcements is cut off at a welding point, but the condition that the welding point is not damaged is required, but in actual operation, the condition is difficult to meet, the other vertical reinforcement is cut off at the welding point, no matter what means is adopted, the damaged welding point is unavoidable, the welding point is not damaged, the cutting position is a certain distance away from the welding point, namely, the cut-off residual reinforcement prevents the two fulcrums of the transverse reinforcements from approaching the vertical reinforcements to be detected, but the clearance between the fulcrums of the transverse reinforcements is in violation of the specification that the clearance between the fulcrums of the transverse reinforcements is as small as possible in the standard, namely, the transverse reinforcements can generate large bending deformation and shaking in the process of being pulled by the single vertical reinforcement, and the accuracy of the shearing resistance test is directly influenced. 2. According to the regulations of the above industry standard, the test result accords with the yield force value regulated by the tensile steel bars with the shearing resistance V being equal to or greater than 0.3 times, but when the prior art is actually tested, only one vertical steel bar has the yield force multiplied by the regulated yield strength, and obviously the yield force is not the shearing resistance data of the parallel steel bars, even if the actual welding point is presumed to bear the shearing resistance, the welding point area of the other truncated vertical steel bar is larger than the welding point area of one vertical steel bar, but the presumption is not the test itself, and the accuracy of the test result is clearly questioned. 3. The lower clamping head of the existing testing machine can only clamp a single vertical stressed steel bar, but cannot clamp the parallel bars, and cannot apply force to the parallel bars. 4. In the prior art, the welding spot shearing resistance test device for the steel bar welding net basically stretches a single vertical steel bar to enable the axes of the upper chuck and the lower chuck to be on the same plumb line, but if the steel bar is stretched, the axes of the upper chuck and the center line of the steel bar are not guaranteed to be on the same plumb line, so that the accuracy of the shearing resistance test result is affected. 5. The welding spot shearing resistance test device for the steel bar welding net in the prior art is easy to interfere with the parallel bars so as to influence the accuracy of the shearing resistance test result.
Disclosure of Invention
The invention aims to solve the technical problem of providing a steel bar welding net parallel rib welding spot shear force resistance test device which can not damage welding spots of shear force resistance test samples and can detect parallel vertical steel bars.
The invention provides a steel bar welding net welding spot shearing resistance testing device, which comprises a steel hook for placing a transverse steel bar of a shearing resistance sample, an upper chuck of a shearing resistance testing machine for clamping the top end of the steel hook and a lower chuck of the bottom end of a vertical steel bar for clamping the shearing resistance sample, wherein a first horizontal U-shaped notch for accommodating the vertical steel bar is formed in a hook body of the steel hook for accommodating the transverse steel bar, and the steel hook is divided into a clamping part and a body part, and the clamping part is hinged with the body part; the lower clamping head is a clamping head capable of clamping two parallel vertical steel bars of a shearing resistance sample.
After the structure is adopted, the shear resistance test device for the reinforcing steel bar welding net welding point has the following advantages: the lower clamping head can clamp two parallel vertical steel bars, the experimental device can effectively apply force to the parallel bars, the relative positions of the clamping part and the body part can be adjusted by hinging, so that the axis of the clamping part and the central line of the parallel bars are ensured to be on the same plumb line, the vertical steel bars of the shearing resistance test sample are two parallel vertical steel bars, the difficult process of cutting off one vertical stress steel bar in the parallel bars is avoided, the test sample is more in line with the actual working state and working condition of the steel bar welding net, the experimental reliability of the experimental device on the parallel bars is strong, the accuracy of the shearing resistance test of the welding net parallel bars is greatly improved, and namely the accuracy of the measurement result is greatly improved.
Further, the width of the first horizontal U-shaped notch is larger than the width of the two parallel vertical steel bars, and the width dimension of the first horizontal U-shaped notch is preferably 0.2-0.6 mm larger than the width dimension of the two accommodated parallel vertical steel bars. After the structure is adopted, the steel hook is prevented from interfering two parallel vertical steel bars, the accuracy of a steel bar welding net welding bar welding spot shearing resistance test is further improved, and the accuracy of a measuring result is further improved.
Further, two parallel vertical steel bars of the shear resistance test sample are positioned at the inner sides of the first horizontal U-shaped notch, and the transverse steel bars of the shear resistance test sample are positioned at the outer sides of the two parallel vertical steel bars. After adopting above structure, under the prerequisite that the axis at the top of steel couple and the central line of two vertical reinforcing bars side by side are on same vertical, the mechanical properties of steel couple coupler body department is better, and the reliability of work is stronger, and the accuracy of experimental result is higher.
Further, the hook body of the steel hook for placing the transverse steel bar is a concave arc surface, an arc sliding block matched with the arc surface is slidingly matched on the arc surface, the top surface of the arc sliding block is an arc groove for placing the transverse steel bar, and a second horizontal U-shaped notch for accommodating two parallel vertical steel bars is formed in the arc sliding block. After the structure is adopted, the positions of the transverse steel bars relative to the front and rear directions of the steel hooks are adjustable, interference of the arc-shaped sliding blocks on two parallel vertical steel bars, namely parallel bars, can be effectively avoided, the axis of the upper end of the steel hook and the central line of the two parallel vertical steel bars are better ensured to be on the same plumb line, and the accuracy of the measurement result of the parallel bar welding spot shearing resistance test is further ensured.
Further, the width of the second horizontal U-shaped notch is greater than the width of the first horizontal U-shaped notch. After the structure is adopted, interference of the arc-shaped sliding blocks on the parallel ribs can be avoided more effectively. Further ensuring the accuracy of the measurement result of the shearing resistance test of the welding points of the parallel ribs.
Further, the upper portion of clamping part is the cylinder, and one of the lower part of clamping part and body portion top is flat piece, has the vertical U font breach that supplies flat piece activity to insert on the other, has the hinge hole that corresponds each other on flat piece and the both sides wall of vertical U font breach, and the hinge in the hinge hole is parallel arrangement with the transverse reinforcement of shear force resistant sample. After the structure is adopted, the hook body of the steel hook for accommodating the transverse steel bars can rotate back and forth along the axis of the hinge shaft, so that the axis of the upper chuck and the central lines of the two parallel vertical steel bars are always kept on the same vertical line, and the accuracy of the measurement result of the shearing resistance test of the welding points of the two parallel vertical steel bars, namely the parallel steel bars, is further improved.
Further, the lower chuck has the structure that: the left clamp head body and the right clamp head body are respectively and detachably connected with a first left half clamp block and a first right half clamp block, two semicircular holes which are matched with the respective radius shapes of the two parallel vertical steel bars in shape are respectively formed at the joint of the first left half clamp block and the first right half clamp block, and a first gap is reserved at the joint of the first left half clamp block and the first right half clamp block after the two parallel vertical steel bars are tightly held. After the structure is adopted, the lower clamping head can reliably clamp the parallel bars, effectively apply force to the parallel bars, and clamp a plurality of parallel bars with different diameters such as 10mm and 12mm by one clamping head.
Further, the structure of the upper chuck is as follows: the left chuck body and the right chuck body are respectively and detachably connected with a second left half clamping block and a second right half clamping block, a semi-circular hole with a shape matched with the shape of the radius of the cylinder is respectively formed at the butt joint of the second left half clamping block and the second right half clamping block, and a second gap is reserved at the butt joint of the second left half clamping block and the second right half clamping block after the cylinder is tightly held. After the structure is adopted, the upper clamping head can reliably clamp the upper end of the steel hook, such as a cylinder, and the axis of the cylinder and the central line of two parallel vertical steel bars can be better ensured to be on the same plumb line.
The invention aims to solve the other technical problem by providing a method for testing the shearing resistance of welding spots of the reinforcing steel bar welding net by adopting the device in any one of the technical proposal, and the method can not only damage the welding spots, but also detect the parallel vertical reinforcing steel bars.
The invention provides a method for testing shearing resistance of a welding joint of a reinforcing steel bar welding net by adopting the device in any one of the technical schemes, which comprises the following steps:
(1) intercepting a cross shear resistant sample comprising a transverse steel bar and two parallel vertical steel bars from a finished steel bar welding net;
(2) placing the transverse steel bars of the shear-resistant test sample on the steel hooks, wherein the lower parts of the two parallel vertical steel bars extend below the first horizontal U-shaped notch;
(3) clamping the upper ends of the steel hooks by using an upper chuck of the shearing resistance tester, and clamping the bottom ends of two parallel vertical steel bars of the shearing resistance test sample by using a lower chuck of the shearing resistance tester;
(4) starting the testing machine, wherein the lower clamping head of the testing machine is pulled downwards in a straight line and blocked by the transverse steel bars, so that the welding points of the transverse steel bars and the two parallel vertical steel bars in the shear-resistant test sample are subjected to shearing force, and the displayed shearing force value is read;
(5) the theoretical shear value of the sample is calculated by adopting the following formula: v is more than or equal to 2 multiplied by 0.3fykAs, wherein fyk is a standard value of the yield strength of the steel bar, and As is the cross-sectional area of one steel bar; and comparing the calculated theoretical shear force value of the sample with a shear force value read by a testing machine, wherein the shear force value read by the testing machine is larger than or equal to the theoretical shear force value, judging that the cross-shaped shear force resistant sample is qualified, and judging that the cross-shaped shear force resistant sample is unqualified when the shear force value read by the testing machine is smaller than the theoretical shear force value.
After the steps are adopted, the method establishes a new judging method of the parallel reinforcement shearing resistance, a new calculation formula is provided, the parallel reinforcement can be effectively forced by using a test device, the relative position of the clamping part of the steel hook and the body part can be adjusted in a hinged connection mode, so that the axis of the clamping part and the central line of the parallel reinforcement are ensured to be on the same vertical line, two vertical reinforcements of the shearing resistance sample are parallel, the difficult procedure of cutting one vertical stressed reinforcement in the parallel reinforcement is avoided, the sample better accords with the actual working state and working condition of a reinforcement welding network, the reliability of the parallel reinforcement sample experiment is strong by adopting the device, and the accuracy of the reinforcement welding network parallel reinforcement welding spot shearing resistance test is greatly improved, namely the accuracy of the measurement result is greatly improved.
Further, the method comprises the steps of,
in the step (2), transverse steel bars of the shear-resistant test sample are placed in an arc-shaped groove of an arc-shaped sliding block, two parallel vertical steel bars are arranged on the inner side, the transverse steel bars are arranged on the outer side, the two parallel vertical steel bars downwards penetrate through a second horizontal U-shaped notch and a first horizontal U-shaped notch, and the lower part of the transverse steel bars extends below the first horizontal U-shaped notch;
in the step (3), the cylinder of the steel hook is clamped by an upper clamping head of the shearing resistance tester.
After the steps are adopted, the positions of the transverse steel bars in the front-rear direction relative to the steel hooks are adjustable due to the adjusting action of the hinge shaft and the arc-shaped sliding blocks, interference of the arc-shaped sliding blocks on the parallel steel bars is effectively avoided, the axis of the cylinder of the clamping part and the central line of two parallel vertical steel bars are better ensured to be on the same plumb line, and the accuracy of the measuring result of the parallel steel bar welding spot shearing resistance test is further ensured.
Drawings
Fig. 1 is a schematic diagram of a cross shear resistance sample structure detected in a reinforcing steel bar welding mesh welding spot shear resistance test device.
Fig. 2 is a schematic diagram of a front sectional structure of a part of a structure of a reinforcing steel bar welding mesh welding spot shear resistance test device according to the invention.
Fig. 3 is a schematic left-view structure of a joint between a clamping part and a body part of a steel hook in the invention.
FIG. 4 is a schematic view showing a structure of a hook body of a steel hook according to the present invention in a cross-sectional view
Fig. 5 is a schematic diagram of a cross-sectional structure of an upper chuck in the reinforcing steel bar welding mesh welding spot shearing resistance test device.
Fig. 6 is a schematic view of the elevation and cross-section structure of the lower clamping head in the reinforcing steel bar welding net welding spot shearing resistance test device.
The shear resistance test specimen shown in the figure 1, the shear resistance test specimen 2, the transverse reinforcing steel bars 3, two parallel vertical reinforcing steel bars 4, the central line of the parallel reinforcing steel bars 5, an upper clamping head 6, a clamping part 7, a hinge shaft 8, a steel hook 9, a body part 10, an arc-shaped sliding block 11, a lower clamping head 12, a vertical U-shaped notch 13, a cylinder 14, a flat block 15, a first horizontal U-shaped notch 16, a second horizontal U-shaped notch 17, a first left half clamping block 18, a first right half clamping block 19, two semicircular holes 20, a first gap 21, a second left half clamping block 22, a second right half clamping block 23, a semicircular hole 24 and a second gap.
Detailed Description
The following describes the embodiments of the present invention further with reference to the drawings. It should be noted that these embodiments are described herein for aiding in the understanding of the present invention, but are not to be construed as limiting the present invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 2, 3 and 4
The invention relates to a steel bar welding mesh welding spot shearing resistance test device, which comprises a steel hook 8 for placing transverse steel bars 2 of a shearing resistance sample 1, an upper chuck 5 of a shearing resistance test machine for clamping the top ends of the steel hook 8, and a lower chuck 11 for clamping the bottom ends of vertical steel bars of the shearing resistance sample 1, wherein a first horizontal U-shaped notch 15 for accommodating the vertical steel bars is formed in the hook body of the steel hook 8 for accommodating the transverse steel bars. Of course, the device for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh and the reinforcing steel bar welded mesh also comprises a driving device such as a cylinder for driving the lower clamping head 11 to do linear pulling motion. The test device may also be referred to as an experimental device or a detection device.
The chuck body of the upper chuck 5 generally adopts a left half and a right half of a wedge structure or a conical structure, is large at the upper part and small at the lower part, is generally matched with a wedge sleeve or a conical sleeve with the same size at the upper part, and is pulled more tightly when pulled down. The clamping block is generally movably connected with the left and right half clamping blocks of the chuck body with the left and right half wedge-shaped structures. The movable connection is that the inner side of the chuck body of the left half wedge-shaped structure and the right half wedge-shaped structure is provided with a transverse dovetail groove, and the outer sides of the left half clamping block and the right half clamping block are provided with dovetail sliding blocks which are spliced with the dovetail grooves.
The chuck body of the lower chuck 11 is also generally in a left-right half wedge structure or a conical structure, is large at the lower part and small at the upper part, is generally matched with a wedge sleeve or a conical sleeve which is large at the upper part and small at the lower part, and is pulled more tightly when pulled down. The clamping block is generally movably connected with the left and right half clamping blocks of the chuck body with the left and right half wedge-shaped structures. The movable connection is that the inner side of the chuck body of the left half wedge-shaped structure and the right half wedge-shaped structure is provided with a transverse dovetail groove, and the outer sides of the left half clamping block and the right half clamping block are provided with dovetail sliding blocks which are spliced with the dovetail grooves.
The above structure is the same as the prior art. The invention relates to a shearing resistance test device for a reinforcing steel bar welding net welding point, which comprises the following components:
as shown in fig. 1, the shear resistant test specimen 1 to be tested is cut into a cross shape, the vertical bars are two parallel vertical bars 3, wherein the length of the two parallel vertical bars above the transverse bar 2 can be shorter than the length of the transverse bar 2, and the length of the two parallel vertical bars below the transverse bar 2 can be longer than the length of the transverse bar 2, so as to facilitate the clamping of the lower clamping head 11. The diameters of the two parallel vertical steel bars 3 are generally the same.
As shown in fig. 2, 3, 4, 5 and 6
The steel hook 8 is divided into a clamping part 6 at the top end and a rest body part 9, and the upper part of the clamping part 6 is a cylinder 13. The clamping part 6 is hinged, i.e. hinged, to the body part 9. One of the lower part of the clamping part 6 and the top of the body part 9 is a flat block, the other is provided with a vertical U-shaped notch for the movable insertion of the flat block, two side walls of the flat block and the vertical U-shaped notch are provided with hinge holes corresponding to each other, and a hinge shaft 7 in the hinge hole is arranged in parallel with the transverse steel bar 2 of the shear-resistant test sample 1. If the lower part of the clamping part 6 is a vertical U-shaped notch 12 with a downward notch, the top of the body part 9 is a flat block 14, the flat block 14 is movably inserted into the vertical U-shaped notch 12, the hinge shaft 7 is movably matched with the hinge holes on the two walls of the vertical U-shaped notch 12 and the hinge holes of the flat block, external threads can be arranged on the two ends of the hinge shaft 7 extending out of the hinge holes, and both ends of the hinge shaft 7 are locked by nuts. Of course, nuts at two ends can be omitted, the hinge holes on the two walls of the vertical U-shaped notch 12 of the clamping part 6 and the hinge shaft 7 can be in interference fit, namely relatively fixed, and the hinge shaft 7 and the hinge hole of the flat block 14 can be in movable fit. I.e. the flat blocks 14 are rotatable relative to the hinge shaft 7. The hinge shaft 7 in the hinge hole is parallel to the transverse steel bars 2 of the shear-resistant test sample 1, namely the hook body 8 on which the shear-resistant test sample 1 is placed can rotate around the hinge shaft 7 so that the central lines of two parallel vertical steel bars, namely the central line 4 of the parallel steel bars and the axis of the cylinder 13, are always kept on the same plumb line, thereby ensuring the accuracy of the detection result.
Of course, the vertical U-shaped notch at the lower part of the clamping part 6 can be exchanged with the flat block at the top of the body part 9. If the top of the body part is a vertical U-shaped notch with an upward notch, the lower part of the clamping part is a flat block, the flat block is movably inserted into the vertical U-shaped notch, external threads can be arranged at two ends of the hinge shaft extending out of the hinge hole, and both ends of the hinge shaft are locked by nuts. I.e. the flat block can rotate relative to the hinge shaft. Of course, the nuts at two ends can be omitted, the two hinge holes on the two walls of the vertical U-shaped notch at the top of the body part can be in interference fit with the hinge shaft, namely, the hinge shaft can be in movable fit with the hinge holes on the two walls of the vertical U-shaped notch and the hinge holes of the flat block, the hinge shaft can be in movable fit with the hinge holes of the flat block, of course, the hinge shaft can be in interference fit with the holes of the flat block, namely, the hinge shaft can be in relative fixation, and the hinge shaft can be in movable fit with the two hinge holes on the two walls of the vertical U-shaped notch, namely, the hinge shaft can be in relative rotation.
The lower clamping head 11 is a clamping head capable of clamping two parallel vertical steel bars 3 of the shear-resistant test sample 1.
The structure of the lower chuck is preferably as follows: the left chuck body and the right chuck body are respectively and detachably connected with a first left half clamping block 17 and a first right half clamping block 18, and the detachable connection is movably spliced with the dovetail groove through the transverse dovetail sliding block. The butt joint of the first left half clamping block 17 and the first right half clamping block 18 is respectively provided with two semicircular holes 19 with the shapes matched with the respective radius shapes of the two parallel vertical steel bars 3, and a first gap 20 is reserved at the butt joint of the first left half clamping block 17 and the first right half clamping block 18 after the two parallel vertical steel bars 3 are tightly held. The two semicircular holes 19 can be understood as two tangential semicircular surfaces, if the clamping diameter is 10mm and 12mm, the radius shape and the size of each semicircle can be matched with those of the 12mm reinforcing steel bar, so that the reinforcing steel bar with the diameter of 12mm and the reinforcing steel bar with the diameter of 10mm can be used commonly, and a first gap 20 is reserved at the butt joint position of the first left half clamping block 17 and the first right half clamping block 17 after the two parallel vertical reinforcing steel bars 3 are tightly clamped, for example, a gap of 6-10 mm can be reserved between two clamped end surfaces.
The structure of the lower chuck can also be as follows: the left chuck body and the right chuck body are not provided with half clamping blocks, but two semicircular holes with the shapes matched with the respective radius shapes of the two parallel vertical steel bars are directly formed in the butt joint position on the body, and a gap is reserved at the butt joint position after the left chuck body and the right chuck body tightly hold the two parallel vertical steel bars.
Anti-slip concave-convex patterns can be arranged in the two semicircular holes of the first left half clamping block 17, the first right half clamping block 18, the left clamping head body and the right clamping head body respectively.
The structure of the lower chuck can also be as follows: the butt joint surfaces of the butt joint parts of the first left half clamping block 17 and the first right half clamping block 18 or the left clamping head body and the right clamping head body can be respectively and directly provided with anti-skid concave-convex patterns, namely two semicircular holes are not arranged, and the anti-skid concave-convex patterns are used for directly holding two parallel vertical steel bars. Of course, the above first embodiment with two semicircular holes is preferred.
The structure of the upper chuck is preferably as follows: the left and right chuck bodies are respectively and detachably connected with a second left half clamping block 21 and a second right half clamping block 22, the butt joint of the second left half clamping block 21 and the second right half clamping block 22 is respectively provided with a semicircular hole 23 with the shape matched with the radius of the cylinder, and a second gap 24 is reserved at the butt joint of the second left half clamping block 21 and the second right half clamping block 22 after the cylinder 13 is tightly held. For example, a gap of 6-10 mm may be left between the two clamped end faces.
The structure of the upper chuck can be as follows: the left chuck body and the right chuck body are not provided with half clamping blocks, but are directly provided with a semicircular hole with the shape matched with the radius shape of each of the two parallel vertical steel bars, and a gap is reserved at the butt joint of the left chuck body and the right chuck body after the left chuck body and the right chuck body tightly hold the two parallel vertical steel bars.
Anti-slip concave convex patterns can be arranged in a semicircular hole 23 of each of the second left half clamping block 21, the second right half clamping block 22, the left clamping head body and the right clamping head body.
The structure of the upper chuck can be as follows: the butt joint surfaces of the butt joint parts of the second left half clamping block and the second right half clamping block or the left clamping head body and the right clamping head body can be respectively and directly provided with anti-skid concave-convex patterns, namely, a semicircle hole is not arranged, and the cylinder is directly held by the anti-skid concave-convex patterns. Of course, the above first embodiment with a semicircular hole is preferred.
The width of the first horizontal U-shaped notch 15 is larger than the width of two parallel vertical steel bars 3, namely the width of the parallel steel bars, and the width dimension of the first horizontal U-shaped notch 15 is preferably 0.2-0.6 mm larger than the width dimension of the two accommodated parallel vertical steel bars 3. The hook body of the transverse steel bar 2 is a concave arc surface, the arc surface is slidably matched with an arc slide block 10 matched with the arc surface, the top surface of the arc slide block 10 is an arc groove for placing the transverse steel bar, the arc slide block 10 is provided with a second horizontal U-shaped notch 16 for accommodating two parallel vertical steel bars, namely parallel bars, the width of the second horizontal U-shaped notch 16 is larger than that of the first horizontal U-shaped notch 15, and if the width of the second horizontal U-shaped notch 16 is larger than that of the first horizontal U-shaped notch 15 by 2mm, the effect is that interference on parallel bars in the stretching process is avoided. The two parallel vertical steel bars 3 of the shear resistance test sample 1 are positioned at the inner sides of the first horizontal U-shaped notch 15, and the transverse steel bars 2 of the shear resistance test sample 1 are positioned at the outer sides of the two parallel vertical steel bars 3. The two parallel vertical steel bars, namely parallel bars, above the transverse steel bars 2 of the cross-shaped shearing resistance test sample 1 are free ends, do not contact any part in the experimental device, do not bear shearing force in the experiment, and have the length of about 150 mm. The supporting length of the transverse steel bars 2 on the arc-shaped sliding blocks on the two sides is preferably more than 25 mm. It will be understood that the sliding of the arc-shaped slider 10 and the arc-shaped surface, that is, the displacement of the transverse bar 2 relative to the hook body, refers to the radial or circumferential displacement of the transverse bar 2, that is, the direction of rotation about the axis of the hinge shaft 7, and does not refer to the axial displacement of the transverse bar 2, that is, the transverse bar may not generate axial displacement on the arc-shaped slider 10 relative to the hook body. Therefore, structures for preventing axial displacement, such as axial limiting lines or arc strips, can be arranged on the transverse reinforcing steel bars and the arc-shaped sliding blocks and the hook bodies, so that the transverse reinforcing steel bars can radially displace or circumferentially displace relative to the arc-shaped sliding blocks and the arc-shaped sliding blocks but not axially displace relative to the hook bodies.
Of course, the above is preferable, and the transverse reinforcement bars can also be directly placed on the hook body of the steel hook.
The invention adopts the method for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh, which adopts any one of the above devices, and adopts the following steps:
(1) and a cross-shaped shear-resistant sample 1 comprising a transverse steel bar 2 and two parallel vertical steel bars 3 is cut from the finished steel bar welding net. Because the parallel ribs are cut off in a parallel way, the prior art tools and methods, such as shearing by a shearing machine or cutting by an oxygen cutting tool, are adopted for cutting, and the working procedure has no technical difficulty.
(2) And placing the transverse steel bars 2 of the shear-resistant test sample 1 on the steel hooks 8, for example placing the transverse steel bars 2 of the shear-resistant test sample 1 in the arc grooves of the arc slide blocks 10, wherein the two parallel vertical steel bars 3 are arranged on the inner side, the transverse steel bars 2 are arranged on the outer side, the two parallel vertical steel bars 3 downwards pass through the second horizontal U-shaped notch 16 and the first horizontal U-shaped notch 15, and the lower part of the two parallel vertical steel bars extends below the first horizontal U-shaped notch 15.
(3) The upper ends of the steel hooks 8, such as the cylinders 13, are clamped by the upper clamping heads 5 of the shearing resistance tester, and the bottom ends of the two parallel vertical steel bars 3 of the shearing resistance test sample 1 are clamped by the lower clamping heads 11 of the shearing resistance tester.
(4) Starting the testing machine, wherein the lower clamping head 11 of the testing machine is pulled downwards in a straight line and blocked by the transverse steel bars 2, so that the welding points of the transverse steel bars 2 and the two parallel vertical steel bars 3 in the shear-resistant test sample 1 are subjected to shearing force, and the displayed shearing force value is read.
The hinge shaft structure and the sliding block are adopted to generate a sliding effect, namely, the positions of the transverse reinforcing steel bars relative to the steel hooks in the front-back direction are adjustable due to the adjusting effect of the hinge shaft and the arc-shaped sliding block, so that the axial line of the cylinder and the central line of two parallel vertical reinforcing steel bars can be better ensured to be on the same vertical line.
(5) The theoretical shear value of the sample is calculated by adopting the following formula: v is more than or equal to 2 multiplied by 0.3fykAs, wherein fyk is a standard value of the yield strength of the steel bar, and As is the cross-sectional area of one steel bar; and comparing the calculated theoretical shear force value of the sample with a shear force value read by a testing machine, wherein the shear force value read by the testing machine is larger than or equal to the theoretical shear force value, judging that the cross-shaped shear force resistant sample is qualified, and judging that the cross-shaped shear force resistant sample is unqualified when the shear force value read by the testing machine is smaller than the theoretical shear force value.
This step expands on the theory: according to the national standard GB/T1499.3 reinforcing steel bar for reinforced concrete and the industry standard JGJ114-2014, the single-reinforcement discrimination standard is the yield force specified by one reinforcing steel bar with the theoretical shear force value V being more than or equal to 0.3 times, namely, V being more than or equal to 0.3fykAs. The parallel bars are two steel bars under the action of pulling force, so that V is more than or equal to 2 multiplied by 0.3fykAs, namely V is more than or equal to 0.6fykAs. fyk stress N/mm 2 Standard value of Mpa yield strength. For example: the diameter is 10mm, and V is more than or equal to 2 multiplied by 0.3 multiplied by the standard value of the yield strength of the steel bar is 400N/mm 2 ＝fyk。V≥2×0.3×400×π/4×10 2 = 18849.6 n=18.85 kN. Those skilled in the art will appreciate that V is the shear resistance of the measured sample in KN.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A method for testing shearing resistance of welding points of reinforcing steel bar welded mesh is characterized by comprising the following steps: the method comprises the following steps:
(1) a cross shear resistant sample (1) comprising a transverse steel bar (2) and two parallel vertical steel bars (3) is cut from a finished steel bar welding net;
(2) the transverse steel bars (2) of the shear-resistant test sample (1) are placed on the steel hooks (8), and the lower parts of the two parallel vertical steel bars (3) extend below the first horizontal U-shaped notch (15);
(3) the upper ends of the steel hooks (8) are clamped by an upper clamping head (5) of the shearing resistance tester, and the bottom ends of two parallel vertical steel bars (3) of the shearing resistance test sample (1) are clamped by a lower clamping head (11) of the shearing resistance tester;
(4) starting the testing machine, wherein a lower clamping head (11) of the testing machine is pulled downwards and linearly and blocked by the transverse steel bars (2), so that the welding points of the transverse steel bars (2) and the two parallel vertical steel bars (3) in the shear-resistant test sample (1) are subjected to shearing force, and the displayed shearing force value is read;
(5) the theoretical shear value of the sample is calculated by adopting the following formula: v is greater than or equal to 2X 0.3f yk A s Wherein f yk Is the standard value of the yield strength of the steel bar, A s Is the cross-sectional area of a steel bar; comparing the calculated theoretical shear force value of the sample with a shear force value read by a testing machine, wherein the shear force value read by the testing machine is larger than or equal to the theoretical shear force value, judging that the cross-shaped shear force resistant sample is qualified, and judging that the cross-shaped shear force resistant sample is unqualified when the shear force value read by the testing machine is smaller than the theoretical shear force value;
the method adopts the steel bar welding net welding spot shearing resistance test device, and comprises a steel hook (8) for placing a transverse steel bar (2) of a shearing resistance sample (1), an upper chuck (5) of a shearing resistance test machine for clamping the top end of the steel hook (8) and a lower chuck (11) for clamping the bottom end of a vertical steel bar of the shearing resistance sample (1), wherein a first horizontal U-shaped notch (15) for accommodating the vertical steel bar is formed in a hook body of the steel hook (8) for accommodating the transverse steel bar (2), the steel hook (8) is divided into a clamping part (6) and a body part (9), and the clamping part (6) is hinged with the body part (9); the lower clamping head (11) is a clamping head capable of clamping two parallel vertical steel bars (3) of the shearing resistance test sample (1);
the hook body of the steel hook (8) for placing the transverse steel bar (2) is a concave arc surface, an arc slide block (10) matched with the arc surface is in sliding fit on the arc surface, the top surface of the arc slide block (10) is an arc groove for placing the transverse steel bar (2), and a second horizontal U-shaped notch (16) for accommodating two parallel vertical steel bars (3) is formed in the arc slide block (10);
the lower chuck (3) has the structure that: the left clamp head body and the right clamp head body are respectively and detachably connected with a first left half clamp block (17) and a first right half clamp block (18), two semicircular holes (19) which are matched with the respective radius shapes of the two parallel vertical steel bars (3) in shape are respectively formed in the butt joint positions of the first left half clamp block (17) and the first right half clamp block (18), and a first gap (20) is reserved in the butt joint positions of the first left half clamp block (17) and the first right half clamp block (18) after the two parallel vertical steel bars (3) are tightly held.
2. The method for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh, as set forth in claim 1, wherein: the width dimension of the first horizontal U-shaped notch is 0.2-0.6 mm larger than the width dimension of the two accommodated parallel vertical steel bars.
3. The method for testing the shearing resistance of welding points of a reinforcing steel bar welded mesh according to claim 1 or 2, wherein the method comprises the following steps of: two parallel vertical steel bars (3) of the shear resistance sample (1) are positioned at the inner sides of the first horizontal U-shaped notch (15), and the transverse steel bars (2) of the shear resistance sample (1) are positioned at the outer sides of the two parallel vertical steel bars (3).
4. A method of testing the shear resistance of a welded mesh joint of reinforcement bars according to claim 3, wherein: the width of the second horizontal U-shaped notch (16) is larger than that of the first horizontal U-shaped notch (15).
5. The method for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh, as set forth in claim 1, wherein: the upper portion of clamping part (6) is cylinder (13), and one of the lower part of clamping part (6) and body portion (9) top is the flat piece, has the vertical U font breach that supplies flat piece activity male on the other, has the hinge hole that corresponds each other on flat piece and the both sides wall of vertical U font breach, hinge (7) in the hinge hole and transverse reinforcement (2) parallel arrangement of shear force resistant test sample (1).
6. The method for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh, as set forth in claim 1, wherein: the upper chuck (5) has the structure that: the left chuck body and the right chuck body are respectively and detachably connected with a second left half clamping block (21) and a second right half clamping block (22), a semicircular hole (23) with the shape matched with the radius shape of the cylinder (13) is respectively formed at the joint of the second left half clamping block (21) and the second right half clamping block (22), and a second gap (24) is reserved at the joint of the second left half clamping block (21) and the second right half clamping block (22) after the cylinder is tightly held.
7. The method for testing the shearing resistance of the welding points of the reinforcing steel bar welded mesh, as set forth in claim 1, wherein:
in the step (2), transverse steel bars (2) of the shear-resistant test sample (1) are placed in arc grooves of an arc-shaped sliding block (10), two parallel vertical steel bars (3) are arranged on the inner side, the transverse steel bars (2) are arranged on the outer side, the two parallel vertical steel bars (2) downwards penetrate through a second horizontal U-shaped notch (16) and a first horizontal U-shaped notch (15), and the lower parts of the two parallel vertical steel bars extend below the first horizontal U-shaped notch (16);
in the step (3), the cylinder (13) of the steel hook (8) is clamped by the upper clamping head (5) of the shearing resistance tester.
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| CN110595919B (en) * | 2019-07-19 | 2022-04-29 | 江阴市建鑫金属有限公司 | Method for testing fatigue strength of steel bar welded mesh |
| CN110631916B (en) * | 2019-11-01 | 2022-04-08 | 山东精准产品质量检测有限公司 | Cold rolling ribbed steel bar detection device |
| CN116296893B (en) * | 2023-03-01 | 2023-09-15 | 绍兴弘信工程检测技术有限公司 | Shear test equipment and detection method for reinforcing mesh |
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