CN109826369B - Full-closed fabricated stirrup with measurable full-length strain - Google Patents
Full-closed fabricated stirrup with measurable full-length strain Download PDFInfo
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- CN109826369B CN109826369B CN201910046559.0A CN201910046559A CN109826369B CN 109826369 B CN109826369 B CN 109826369B CN 201910046559 A CN201910046559 A CN 201910046559A CN 109826369 B CN109826369 B CN 109826369B
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Abstract
The invention discloses a full-closed fabricated stirrup with a measurable full-length strain. Including two U shaped steel bars that the structure is the same, every the steel axle sleeve is welded respectively to the free end of U shaped steel bar, two the steel axle sleeve at U shaped steel bar both ends between form wholly, every through a straight section bar connection respectively straight section bar the inside is provided with along the long straight recess that its axial link up, a set of foil gage is pasted at the inner wall interval of long straight recess, the foil gage passes through the wire and connects, the wire stretches out straight section bar outside. The method can effectively improve the adverse factors of the traditional testing technology and improve the accuracy of the calculation of the shear resistance bearing capacity of the stirrup by items, thereby improving the accuracy of the shear resistance bearing capacity formula of the existing design specification.
Description
The technical field is as follows:
the invention relates to a full-closed fabricated stirrup with a measurable full-length strain, belonging to the technology of steel bar performance test. The method is mainly used in the fields of buildings, bridges, water conservancy, traffic and the like.
Background art:
the prediction of the shear resistance of reinforced concrete members has been a very challenging classic problem in the field of structural engineering, and has attracted a large number of scholars for over a century to conduct continuous research. Over the past few decades, there have been many important advances in the exploration of this problem, which, however, has remained recognized as one of the most understandably but most important problems in the field of reinforced concrete. Unlike flexural failure of a tendon, shear failure of a reinforced concrete beam is often characterized by brittle failure, occurs relatively suddenly, lacks aura, and is prone to catastrophic events.
The shear-resistant bearing capacity of the reinforced concrete member consists of the following parts: tension of stirrups, shear stress of concrete in the shear nip, occlusion acting force of aggregates, residual tension stress of shear cracks, pin bolt acting force of longitudinal bars and concrete arch acting force. The existing design specifications divide the above mentioned shear action into two main components: shear-resistant bearing borne by tension of stirrup at shear inclined crackContribution of load
And the contribution of the shear-resistant bearing capacity borne by the concrete
. Therefore, how to accurately obtain the strain value of the stirrup at the shear inclined crack is the key for establishing an accurate calculation formula of the shear bearing capacity of the reinforced concrete member.
Regarding obtaining strain values of stirrups at a shear inclined crack, the existing test methods are mainly classified into four types: in the first type, strain gauges are adhered to the surfaces of the two limbs of the stirrup at half-height. The strain of the stirrup measured by the method is not necessarily the strain of the stirrup at the oblique crack, since the shear oblique crack does not necessarily intersect at the half-height of the stirrup. And secondly, predicting a development path of the shear inclined crack, and sticking a strain gauge on the surface of the stirrup at the intersection point of the predicted crack path and the stirrup. The strain measured by this method is also not necessarily the strain of the stirrup at the true oblique crack. And thirdly, continuously sticking a strain gauge on the surface of the stirrup along the whole length of the stirrup. The method breaks the bond between the stirrup and the concrete, changes the stress performance of the reinforced concrete member, and cannot obtain the shear contribution of the stirrup under the real stress condition. And fourthly, grooving the inside of the stirrup, continuously sticking a strain gauge, and finally lapping the strain gauge with the U-shaped steel bar to form an open type or semi-closed type stirrup. Although the method can obtain the full-length strain of the stirrup, the open type or semi-closed type stirrup structure cannot ensure the effective restraint of the stirrup on the concrete and cannot reflect the real stress condition of the stirrup in the reinforced concrete member.
The above disadvantages result in that the contribution of the true and accurate shear-resisting bearing capacity of the stirrup cannot be obtained for a long time, and the contribution becomes an uncertain factor of the shear-resisting design of the reinforced concrete member, thereby causing adverse effects on the accuracy and safety of the design of the reinforced concrete member.
Disclosure of Invention
The invention aims to provide a full-closed fabricated stirrup with a measurable full-length strain, which aims to improve the adverse factors of the traditional testing technology and improve the accuracy of subentry calculation of the shear-resistant bearing capacity of the stirrup, thereby improving the accuracy of the existing design specification shear-resistant bearing capacity formula.
The above purpose is realized by the following technical scheme:
the utility model provides a measurable full cut-off assembled stirrup of full length strain, includes two U shaped steel bars that the structure is the same, every the steel axle sleeve is welded respectively to the free end of U shaped steel bar, two the steel axle sleeve at U shaped steel bar both ends between form wholly, every through a straight section reinforced bar connection respectively straight section reinforcing bar the inside is provided with along the straight recess of its axial through, a set of foil gage is pasted at the inner wall interval of the straight recess of length, the foil gage passes through the wire and connects, the wire stretches out straight section reinforcing bar outside.
The full-closed fabricated stirrup capable of measuring full-length strain is characterized in that external thread sections are arranged at two ends of the straight section steel bar, and the straight section steel bar penetrates through the steel shaft sleeve and is fixed through nuts assembled on the straight section steel bar.
The full-closed fabricated stirrup with the measurable full-length strain comprises straight-section steel bars and external thread sections, wherein the length of the external thread sections at two ends of each straight-section steel bar is 5-20 mm.
The distance between adjacent strain gauges of the full-closed fabricated stirrup with the measurable full-length strain is 10-50 mm.
The full-closed fabricated stirrup with the measurable full-length strain is characterized in that the straight-section steel bars are ribbed steel bars or smooth round steel bars, and the diameter of the straight-section steel bars is 8-20 mm.
The full-closed fabricated stirrup with the measurable full-length strain comprises a long straight groove, wherein the depth of the long straight groove is 1mm-4mm, and the width of the long straight groove is 6mm-16 mm.
The full-closed fabricated stirrup with the measurable full-length strain is characterized in that the U-shaped steel bar is a ribbed steel bar or a smooth round steel bar, and the diameter of the U-shaped steel bar is the same as that of the straight section steel bar.
The full-closed fabricated stirrup with the measurable full-length strain comprises a steel shaft sleeve, wherein the radial thickness of the steel shaft sleeve is 10mm-20mm, and the length of the steel shaft sleeve is 10mm-50 mm.
Has the advantages that:
compared with the prior art, the invention has the advantages that: on the premise of not damaging the bonding performance of the stirrup and concrete, the full-length strain along the length direction of the stirrup can be measured, the constraint performance of the stirrup on the concrete can be effectively ensured by a full-closed assembly type connection mode, the stirrup is completely manufactured by welding-free assembly type mechanical connection, and the strain gauge damage caused by high welding temperature can be effectively avoided.
1. According to the invention, the grooves are formed in the stirrups, and the strain gauges are continuously adhered, so that the influence of the traditional measurement mode on the bonding performance of the steel bars and the concrete is effectively eliminated.
2. According to the invention, the strain gauge is continuously pasted in the length direction of the inner side of the straight section of the steel bar, so that continuous strain along the whole length of the straight section of the steel bar can be obtained, and the accurate strain value of the stirrup at the intersection of the shear inclined crack and the stirrup can be obtained by positioning the shear inclined crack, so that the actual shearing resistance and bearing capacity contribution of the stirrup can be accurately obtained, and the error of the traditional measurement mode is greatly reduced.
3. According to the invention, the straight section steel bar and the U-shaped steel bar are combined into the full-closed assembly type stirrup in a mechanical connection mode, so that the damage of the strain gauge caused by high welding temperature is effectively avoided, and the readability of the measured data is ensured.
Drawings
Fig. 1 is a perspective view of a straight reinforcing bar according to the present invention.
Fig. 2 is a perspective view of the U-shaped reinforcing bar of the present invention.
FIG. 3 is an exploded view of the fully closed assembled stirrup assembly of the present invention.
Fig. 4 is an assembled perspective view of the full close assembled stirrup of the present invention.
Reference numerals: 1. straight section reinforcing bar 2, U shaped steel muscle 3, foil gage 4, wire 5, steel axle sleeve 6, nut 7, recess 8, external screw thread.
Detailed Description
The present invention will be further illustrated below with reference to specific embodiments, which are to be understood as merely illustrative and not limitative of the scope of the present invention.
As shown in fig. 1, the measurable full cut-off assembled stirrup of full length strain of this embodiment includes two U shaped steel 2 that the structure is the same, every the free end of U shaped steel welds a steel axle sleeve 5 respectively, two the steel axle sleeve at U shaped steel both ends between connect through a straight section reinforcing bar 1 respectively and form wholly, every straight section reinforcing bar the inside is provided with along its axial through's long straight recess 7, a set of foil gage 3 is pasted at the inner wall interval of long straight recess, the foil gage passes through wire 4 and connects, the wire stretches out straight section reinforcing bar outside so that be connected with strain acquisition appearance.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the two ends of the straight section of the steel bar are provided with the external thread sections 8, and the straight section of the steel bar penetrates through the steel shaft sleeve and is fixed through the nuts 6 assembled on the straight section of the steel bar.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the length of the external thread sections at the two ends of the straight section of the steel bar is 5-20 mm.
In the full-length full-closed fabricated stirrup capable of measuring strain in the embodiment, the distance between adjacent strain gauges is 10-50 mm.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the straight-section steel bars are ribbed steel bars or smooth round steel bars, and the diameter of the straight-section steel bars is 8-20 mm.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the depth of the long straight groove is 1mm-4mm, and the width of the long straight groove is 6mm-16 mm.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the U-shaped steel bar is a ribbed steel bar or a plain round steel bar, and the diameter of the U-shaped steel bar is the same as that of the straight steel bar.
In the fully closed fabricated stirrup with the measurable full-length strain in the embodiment, the radial thickness of the steel shaft sleeve is 10mm-20mm, and the length of the steel shaft sleeve is 10mm-50 mm.
The processing process comprises the following steps:
the method for manufacturing the straight section steel bar comprises the following steps: 1. firstly, threads are turned at two ends of a straight section of steel bar, and the length of each thread section is 5-20 mm.
2. The straight bar (cylindrical) is then cut in half (semi-cylindrical) by wire cutting along the longitudinal axis of the straight bar.
3. And respectively lathing grooves on the two sections along the axis direction of the steel bar by linear cutting or punching, wherein the depth of the grooves is 1-4 mm, the width of the grooves is 6-16 mm, and the length of the grooves is the same as that of the straight section of the steel bar.
4. And continuously sticking strain gauges every 10-50 mm on the surface of the groove along the axial direction of the steel bar, and connecting the strain gauges with a lead of the strain gauge.
5. And finally, re-bonding the two split steel bars (semi-cylinders) into a whole (cylinder) through high-strength epoxy glue, and leading out the strain gauge wire from one end of the steel bar or from two ends of the steel bar.
The manufacturing method of the U-shaped steel bar with the steel shaft sleeves at the two ends comprises the following steps: 1. firstly, bending a straight section of steel bar into a U-shaped steel bar with hooks at two ends by a steel bar bending machine or a manual hook pulling bending mode, wherein the angle between the hook section and the straight section is 90 degrees, and the length of the hook section is 50-100 mm.
2. And secondly, the steel shaft sleeve and the U-shaped steel bar hook section are connected into a whole in a welding mode.
The assembling method of the full-length strain full-closed fabricated stirrup capable of measuring is as follows: 1. and connecting two ends of the straight section of the steel bar with matched nuts respectively, and screwing the straight section of the steel bar to the root of the threaded section.
2. Then, two ends of the straight steel bar respectively penetrate through the steel shaft sleeves at the end parts of the two U-shaped steel bars, and one end of each steel shaft sleeve is tightly attached to the nut at the root part of the corresponding thread section.
3. And finally, connecting the thread section of the straight section of the steel bar with another matched nut, screwing the straight section of the steel bar to be tightly attached to the other end face of the steel shaft sleeve, and finally forming the fully-closed assembled U-shaped steel bar.
The working process is as follows:
when strain of the stirrup in the stress deformation process is measured, a strain gauge lead led out from the end part of the straight section of the steel bar is connected with a strain acquisition instrument, and the strain value distribution of the whole length of two limbs of the stirrup can be measured in real time.
Claims (7)
1. The utility model provides a measurable full-length full cut-off assembled stirrup that meets an emergency which characterized in that: the steel bar structure comprises two U-shaped steel bars with the same structure, wherein a steel shaft sleeve is welded at the free end of each U-shaped steel bar, the steel shaft sleeves at the two ends of the two U-shaped steel bars are connected into a whole through a straight section of steel bar, a long straight groove which is through along the axial direction of each straight section of steel bar is arranged in each straight section of steel bar, a group of strain gauges are attached to the inner wall of each long straight groove at intervals, the strain gauges are connected through a lead, and the lead extends out of the straight section of steel bar;
and the two ends of the straight section of the steel bar are provided with external thread sections, and the straight section of the steel bar penetrates through the steel shaft sleeve and is fixed through nuts assembled on the straight section of the steel bar.
2. The full-length, strain-measurable, fully closed fabricated stirrup according to claim 1, wherein: the length of the external thread sections at the two ends of the straight section of the steel bar is 5mm-20 mm.
3. The full length, strain measurable, full closed fabricated stirrup according to claim 1 or 2, wherein: the distance between the adjacent strain gauges is 10mm-50 mm.
4. The full length, strain measurable, full closed fabricated stirrup according to claim 1 or 2, wherein: the straight section steel bar adopts a ribbed steel bar or a smooth steel bar, and the diameter of the straight section steel bar is 8-20 mm.
5. The full length, strain measurable, full closed fabricated stirrup according to claim 1 or 2, wherein: the depth of the long straight groove is 1mm-4mm, and the width of the long straight groove is 6mm-16 mm.
6. The full length, strain measurable, full closed fabricated stirrup according to claim 1 or 2, wherein: the U-shaped steel bar is a ribbed steel bar or a smooth steel bar, and the diameter of the U-shaped steel bar is the same as that of the straight-section steel bar.
7. The full length, strain measurable, full closed fabricated stirrup according to claim 1 or 2, wherein: the radial thickness of the steel shaft sleeve is 10mm-20mm, and the length of the steel shaft sleeve is 10mm-50 mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910046559.0A CN109826369B (en) | 2019-01-18 | 2019-01-18 | Full-closed fabricated stirrup with measurable full-length strain |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910046559.0A CN109826369B (en) | 2019-01-18 | 2019-01-18 | Full-closed fabricated stirrup with measurable full-length strain |
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| CN109826369A CN109826369A (en) | 2019-05-31 |
| CN109826369B true CN109826369B (en) | 2021-03-02 |
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| CN103912027B (en) * | 2014-04-24 | 2015-10-21 | 中国科学院武汉岩土力学研究所 | A kind of fabrication and installation of anchored in situ test and automatic data collection method |
| CN106932250A (en) * | 2017-03-28 | 2017-07-07 | 湖南城市学院 | A kind of regeneration concrete shearing resistance beam |
| CN107843556B (en) * | 2017-12-22 | 2020-07-14 | 西京学院 | Device and method for testing bonding stress between concrete and steel bar |
| CN108444630A (en) * | 2018-03-19 | 2018-08-24 | 中冶建筑研究总院有限公司 | A method of measuring changing rule of the reinforcement stresses along reinforcing bar length direction |
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