CN110907076A - Method for detecting uniform hoop restraining force of circular steel tube concrete column in real time by ultrasonic waves - Google Patents
Method for detecting uniform hoop restraining force of circular steel tube concrete column in real time by ultrasonic waves Download PDFInfo
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- CN110907076A CN110907076A CN201910998345.3A CN201910998345A CN110907076A CN 110907076 A CN110907076 A CN 110907076A CN 201910998345 A CN201910998345 A CN 201910998345A CN 110907076 A CN110907076 A CN 110907076A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/25—Measuring force or stress, in general using wave or particle radiation, e.g. X-rays, microwaves, neutrons
- G01L1/255—Measuring force or stress, in general using wave or particle radiation, e.g. X-rays, microwaves, neutrons using acoustic waves, or acoustic emission
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/30—Columns; Pillars; Struts
- E04C3/34—Columns; Pillars; Struts of concrete other stone-like material, with or without permanent form elements, with or without internal or external reinforcement, e.g. metal coverings
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Abstract
The invention discloses a method for detecting the uniform hoop restraining force of a circular steel tube concrete column in real time by ultrasonic waves. When the axis of the circular steel tube concrete column is pressed, the hoop restraining force is uniformly distributed along the section of the column, the method is based on an ultrasonic stress testing technology, a pair of ultrasonic transmitters and receivers are used for detecting the hoop restraining force, an ultrasonic transmitting sensor is pre-embedded in the center of the section to be measured in the column to transmit ultrasonic waves, an ultrasonic receiving device is arranged on the outer surface of the steel tube with the same cross section to receive a test signal, and then the hoop restraining force when the axis of the circular steel tube concrete column is pressed is detected in real time according to the relation between the received ultrasonic sound-stress sensitivity parameter and the hoop restraining force. The invention has simple operation, intuitive measurement result, simple test device and high sensitivity, can realize the real-time measurement of the restraint force of the hoop in the whole stress process, realize the real-time detection of the restraint force of the hoop in the construction or service process, and also can realize the real-time monitoring of the safety and the health of the structure.
Description
Technical Field
The invention relates to the technical field of ultrasonic nondestructive testing, in particular to a method for detecting the uniform hoop restraining force of a circular steel tube concrete column in real time by ultrasonic.
Background
The steel pipe concrete column is being more and more widely used in practical engineering because of its advantages of high bearing capacity, good earthquake resistance, better fire resistance than steel structure, and convenient construction. The bearing capacity of the steel tube concrete column can generate the effect of 1+1>2, wherein the most important reason is the hoop restraining effect of the steel tube on the core concrete, so that the core concrete is in a three-dimensional compression state, and the compression strength of the concrete is improved. Therefore, the determination of the magnitude of the restraint force of the hoop is very important for deeply researching the mechanical property of the concrete-filled steel tubular column.
Currently, there are a pressure sensor method and a hydraulic pressure simulation method for directly measuring the restraint force of the steel pipe ferrule. However, the core concrete in the steel pipe concrete is in a three-dimensional compression state, the pressure sensor is influenced by longitudinal pressure and circumferential pressure under complex stress, the sensitivity of the pressure sensor is reduced, and the sensitivity of the pressure sensor is also reduced after repeated loading, so that the core concrete is difficult to popularize in practical application; the hydraulic analog method is an analog method, and the test is complicated, the reading is not visual, and the precision is not high. Meanwhile, the hoop restraining force of the steel pipe exists on the interface of the steel pipe and the concrete, the measuring device of the common stress strain cannot be installed, the measuring element can be prevented from being arranged at the interface contact position by adopting an ultrasonic mode, and the measuring device has a good application prospect. At present, no relevant report that the ultrasonic detection technology is used for directly detecting the binding force of the circular steel tube concrete column hoop is found.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for detecting the uniform hoop restraining force of a circular steel tube concrete column in real time by using ultrasonic waves.
In order to achieve the purpose, the method for detecting the uniform hoop restraining force of the circular steel tube concrete column in real time by using ultrasonic waves is characterized by comprising the following steps of: the method comprises the steps that a round steel tube concrete column structure is used as a sensitive element, ultrasonic waves are transmitted to the round steel tube concrete column structure by an ultrasonic transmitting sensor, an ultrasonic receiving device receives a sound wave test signal penetrating through the round steel tube concrete column structure, and the uniform hoop restraining force of a round steel tube on core concrete when the axis of the round steel tube concrete column structure is pressed is accurately detected according to the relation between a received ultrasonic sound-stress sensitivity parameter and the hoop restraining force; the method comprises the following steps:
(1) embedding an ultrasonic emission sensor, wherein the ultrasonic emission sensor is embedded in the center position of a section to be measured in the circular steel tube concrete column to be measured before core concrete is poured;
(2) carrying out a compression test on the round steel tube concrete column to be tested, and carrying out graded loading; in the initial stage of loading, each stage of loading is 1/10 of estimated ultimate load, when the steel pipe enters the yield stage, each stage of load is 1/20 of the ultimate load, the load holding time of each stage is 2-3 min, and an ultrasonic test is carried out after the pointer of the dial plate of the press is stable;
(3) performing ultrasonic testing, namely enabling an ultrasonic receiving device to be in good contact with the outer surface of a measured cross-section steel tube in the round steel tube concrete column to be tested through an ultrasonic coupling agent; during testing, the ultrasonic transmitting sensor transmits ultrasonic waves to the round steel tube concrete column to be tested, the ultrasonic receiving device receives the ultrasonic waves transmitted through the round steel tube concrete column to be tested, and simultaneously, a beam curve corresponding to the transmitted ultrasonic waves is recorded;
(4) the computer analyzes and processes the ultrasonic testing signal received by the ultrasonic receiving device, processes the received sound wave signal by utilizing wavelet analysis, and calculates the weighted frequency domain spectral area parameter by utilizing a formula (1):
in the formula: sjIs 2 ndjAnd (3) measuring the change amplitude value of the frequency domain spectral area of the wavelet component under the scale, and further measuring and calculating the restraint force of the ferrule according to the correlation between the analyzed and processed ultrasonic sound-stress sensitive parameters and the stress.
As a preferred scheme, in the step (1), the ultrasonic transmitting sensor is pre-embedded in the central position of the section to be measured in the core concrete of the circular steel tube concrete column structure to be measured, and the ultrasonic receiving device is arranged on the outer surface of the steel tube with the same cross section of the circular steel tube concrete column structure to be measured.
Further, the ultrasonic testing in the step (3) is detection by an ultrasonic penetration method, and the ultrasonic receiving device is in good contact with the outer surface of the steel tube of the round steel tube concrete column to be tested through an ultrasonic coupling agent during the ultrasonic testing; under the condition of good bonding state of the steel pipe concrete, the condition that ultrasonic waves are diffracted along the steel pipe wall can be avoided.
The working principle of the invention is as follows:
when the concrete filled steel tube is pressed, the hoop restraining force limits the development of micro cracks in the core concrete, the ultrasonic waves transmit through the concrete to cause energy attenuation after reflection, refraction and scattering at a micro crack interface, and the stress state in the concrete filled steel tube column can be sensitively reflected according to the change of various sound wave parameters. When the round steel tube concrete column is pressed in the axis, the hoop restraining force of the steel tube on the core concrete is uniformly distributed along the cross section of the column, so that the hoop restraining force can be detected by using a pair of ultrasonic transmitters and receivers. The method is based on an ultrasonic stress testing technology, adopts an ultrasonic penetration method, takes the circular steel tube concrete column as a sensitive element, utilizes an ultrasonic transmitting sensor to transmit ultrasonic waves to the circular steel tube concrete column, and an ultrasonic receiving device receives an acoustic wave testing signal penetrating through the circular steel tube concrete column. Because the constraint action of the circular steel tube on the core concrete is relatively uniform, only a pair of ultrasonic transmitting and receiving devices needs to be arranged.
The invention has the advantages and beneficial effects that:
compared with the prior art, the invention has the advantages that: the method for detecting the hoop restraining force of the circular steel tube concrete column constructs the relation between the sound-stress sensitive parameter and the hoop restraining force of the steel tube on the core concrete based on the ultrasonic stress test technology, can directly detect the hoop restraining force of the steel tube on the core concrete by only testing the sound wave parameter transmitted through the circular steel tube concrete column under the condition of not damaging a test piece, has simple operation, intuitive measurement result, simple test device and high sensitivity, can realize the actual measurement of the hoop restraining force in the whole stress process of the circular steel tube concrete column, and provides a reliable experimental basis for deep research on the theoretical aspect of the steel tube concrete column; the ultrasonic emission frequency can be adjusted to a higher frequency, so that the hoop restraining force can be detected in real time in the construction or service process of the circular steel tube concrete column, and the safety and the health of the structure can be monitored in real time.
Drawings
FIG. 1 is a schematic cross-sectional view of a detection structure for detecting the uniform hoop restraining force of a circular steel tube concrete column in real time by ultrasonic waves;
fig. 2 is a schematic structural diagram of a detection device for detecting the corresponding restraining force of the uniform hoop of the circular steel tube concrete column in real time by using ultrasonic waves, which is provided by the embodiment of the invention.
In the figure: 1. the device comprises a round steel pipe concrete column to be detected, 2, an ultrasonic transmitting sensor, 3, an ultrasonic receiving device, 4 and a computer.
Detailed Description
The present invention will be further explained in detail with reference to the following embodiments and the accompanying drawings.
Fig. 2 is a schematic structural diagram of a detection device corresponding to the method for detecting the uniform hoop restraining force of the circular steel tube concrete column in real time by using ultrasonic waves. The detection device comprises a round steel tube concrete column 1 to be detected, an ultrasonic emission sensor 2, a signal amplifier device, an ultrasonic receiving device 3 and a computer 4. The circular steel tube concrete column 1 to be detected is preferably formed by pouring self-compacting concrete, the ultrasonic transmitting sensor 2 is embedded in the center of the cross section in the column before core concrete is poured, the ultrasonic receiving device 3 is tightly attached to the outer surface of a steel tube of the cross section in the circular steel tube concrete column 1 to be detected, and preferably, the ultrasonic transmitting sensor 2 and the ultrasonic receiving device 3 are in synchronous working states; further, the ultrasonic receiving sensor 2 is also connected with a computer 4, and the computer 4 is used for analyzing and processing the ultrasonic testing signal received by the ultrasonic receiving device 3, and further measuring and calculating the hoop restraining force according to the correlation between the ultrasonic sound-stress sensitive parameter and the stress after the analysis and processing.
Specifically, the method comprises the following steps:
(1) embedding an ultrasonic transmitting sensor 2, and embedding the ultrasonic transmitting sensor 2 in the central position of a section to be measured in the column before pouring core concrete;
(2) and performing an axis compression test on the round steel tube concrete column 1 to be tested, and adopting graded loading. In the initial stage of loading, each stage of loading is 1/10 of estimated ultimate load, when the steel pipe enters the yield stage, each stage of load is 1/20 of the ultimate load, the load holding time of each stage is about 2-3 min, and an ultrasonic test is carried out after the pointer of the dial plate of the press is stable;
(3) and (3) ultrasonic testing, namely, enabling the ultrasonic receiving device 3 to be in good contact with the outer surface of the steel pipe with the measured cross section in the column through an ultrasonic coupling agent. During testing, the ultrasonic transmitting sensor 2 transmits ultrasonic waves to the round steel tube concrete column 1 to be tested, the ultrasonic receiving device 3 receives the ultrasonic waves which penetrate through the round steel tube concrete column, and meanwhile, a beam curve corresponding to the transmitted ultrasonic waves is recorded.
(4) Processing the received sound wave signal by wavelet analysis, and calculating the weighted frequency domain spectral area parameter by formula (1)
In the formula: sjIs 2 ndjMagnitude of variation of the frequency domain spectral area of the wavelet component at scale. For a certain wall thickness of 2.9mm, diameter of 219mm and internal filling and mixingThe concrete filled steel tubular column with the concrete strength of C40 is tested at 0.2Nu(NuLimit load), 0.35Nu、0.86Nu、1.0NuAnd unloading to 0.87N after limit loaduThe measured spectral area parameter range is 1.125-1.467. According to the calibration result of the correlation between the spectral area parameter and the restraint force of the cuff, the value is 0.35NuThe previous restraining force was close to 0 at 0.86NuIncreasing the time to 2.45MPa, and unloading to 0.87N at the end of loadinguThen, 7.46MPa is reached. The result is compared with the finite element calculation result, and the variation trend of the result and the finite element calculation result is completely consistent.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (3)
1. A method for detecting the uniform hoop restraining force of a circular steel tube concrete column in real time by ultrasonic waves is characterized by comprising the following steps of: the method comprises the steps that a round steel tube concrete column structure is used as a sensitive element, ultrasonic waves are transmitted to the round steel tube concrete column structure by an ultrasonic transmitting sensor, an ultrasonic receiving device receives a sound wave test signal penetrating through the round steel tube concrete column structure, and the uniform hoop restraining force of a round steel tube on core concrete when the axis of the round steel tube concrete column structure is pressed is accurately detected according to the relation between a received ultrasonic sound-stress sensitivity parameter and the hoop restraining force; the method comprises the following steps:
(1) embedding an ultrasonic emission sensor, wherein the ultrasonic emission sensor is embedded in the center position of a section to be measured in the circular steel tube concrete column to be measured before core concrete is poured;
(2) carrying out a compression test on the round steel tube concrete column to be tested, and carrying out graded loading; in the initial stage of loading, each stage of loading is 1/10 of estimated ultimate load, when the steel pipe enters the yield stage, each stage of load is 1/20 of the ultimate load, the load holding time of each stage is 2-3 min, and an ultrasonic test is carried out after the pointer of the dial plate of the press is stable;
(3) performing ultrasonic testing, namely enabling an ultrasonic receiving device to be in good contact with the outer surface of a measured cross-section steel tube in the round steel tube concrete column to be tested through an ultrasonic coupling agent; during testing, the ultrasonic transmitting sensor transmits ultrasonic waves to the round steel tube concrete column to be tested, the ultrasonic receiving device receives the ultrasonic waves transmitted through the round steel tube concrete column to be tested, and simultaneously, a beam curve corresponding to the transmitted ultrasonic waves is recorded;
(4) the computer analyzes and processes the ultrasonic testing signal received by the ultrasonic receiving device, processes the received sound wave signal by utilizing wavelet analysis, and calculates the weighted frequency domain spectral area parameter by utilizing a formula (1):
in the formula: sjIs 2 ndjAnd (3) measuring the change amplitude value of the frequency domain spectral area of the wavelet component under the scale, and further measuring and calculating the restraint force of the ferrule according to the correlation between the analyzed and processed ultrasonic sound-stress sensitive parameters and the stress.
2. The method for detecting the uniform hoop restraining force of the circular steel tube concrete column in real time by using the ultrasonic waves according to claim 1, wherein the method comprises the following steps of: in the step (1), the ultrasonic transmitting sensor is pre-embedded in the central position of the section to be measured in the core concrete of the circular steel tube concrete column structure to be measured, and the ultrasonic receiving device is arranged on the outer surface of the steel tube of the same cross section of the circular steel tube concrete column structure to be measured.
3. The method for detecting the uniform hoop restraining force of the circular steel tube concrete column in real time by using the ultrasonic waves according to claim 1 or 2, wherein the method comprises the following steps: the ultrasonic testing in the step (3) is detection by adopting an ultrasonic penetration method, and the ultrasonic receiving device is in good contact with the outer surface of the steel pipe of the round steel pipe concrete column to be tested through an ultrasonic coupling agent during the ultrasonic testing; under the condition of good bonding state of the steel pipe concrete, the condition that ultrasonic waves are diffracted along the steel pipe wall can be avoided.
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