Stress measurement method and measurement value correction formula setting program

Abstract

To solve problems in prior art, namely to provide a technique for grasping stress of a reinforcing bar by non-destructive measurement without cutting the reinforcing bar in concrete.SOLUTION: A stress measurement method is used to measure stress of steel materials by applying X rays to the steel materials in concrete, and has a polishing condition determination process, a primary polishing process, a secondary polishing process, an X-ray measurement process, and a stress correction process. The polishing condition determination process has a primary test polishing process and a secondary test polishing process, an X-ray test measurement process, a current value determination process, and a correction expression setting process. In the stress correction process, actually measured stress obtained in the X-ray measurement process is corrected by a stress correction expression.SELECTED DRAWING: Figure 1

Claims

1. A method for measuring the stress of steel materials in concrete by irradiating the steel materials with X-rays, A polishing condition determination process to determine the polishing conditions, The correction formula setting process involves setting a measurement correction formula, A concrete cutting process in which a portion of the steel material is exposed by cutting away the concrete, A primary polishing step in which the surface of the exposed steel material is polished using a polishing machine to form a primary polished surface, A secondary polishing step is performed to form a secondary polished surface by performing electropolishing on the primary polished surface, An X-ray measurement step is performed to obtain a measurement value by measuring the secondary polished surface using an X-ray stress measuring device. The measurement value correction step includes correcting the measurement value obtained in the X-ray measurement step with the measurement value correction formula set in the correction formula setting step to determine the stress of the steel material, The aforementioned polishing condition determination step is: A primary test polishing step involves forming a primary test polished surface by polishing multiple steel material samples of the same specifications as the steel material in the concrete using a polishing machine, A secondary test polishing step is performed to form a secondary test polishing surface by performing electrolytic polishing on a plurality of primary test polishing surfaces formed in the primary test polishing step, each with a different current value. An X-ray test measurement step is performed in which multiple steel samples are subjected to different stress states, and the test stress is obtained by measuring the secondary test polished surface for each of the different stress states using the X-ray stress measuring device. The process includes a current value determination step in which a plurality of test stresses obtained in the X-ray test measurement step are compared with a logical stress obtained by calculation or measurement, and the current value for the secondary test polishing surface that yields the test stress that most closely approximates the logical stress is determined as the optimal current value. In the correction formula setting step, the measurement value correction formula is set based on the test stress for each stress state related to the optimal current value obtained in the X-ray test measurement step and the logical stress. In the secondary polishing step, electrolytic polishing is performed using the optimal current value determined in the current value determination step. A stress measurement method characterized by the following features.

2. In the correction formula setting step, a stress coordinate system is set with the logical stress as the first axis and the test stress as the second axis, a regression formula is set based on the combination of the logical stress and the test stress arranged in the stress coordinate system, and the measurement value correction formula is set based on the regression formula. The stress measurement method according to claim 1, characterized by the feature.

3. The polishing condition determination step further comprises a cutting shape determination step for determining the cutting shape, In the aforementioned primary test polishing process, multiple types of cutting shapes are set, and polishing is performed to achieve each of the said cutting shapes. The secondary test polishing surfaces are formed by performing electrolytic polishing on the primary test polishing surfaces relating to different cutting shapes, each at the optimal current value. In the cutting shape determination step, the multiple test stresses obtained as a result of the X-ray test measurement step performed on the secondary test polishing surfaces relating to different cutting shapes are compared with the logical stress, and the cutting shape relating to the primary test polishing surface from which the test stress that most closely approximates the logical stress is obtained is determined as the optimal cutting shape. In the primary polishing step, the polishing is performed to achieve the optimal cutting shape. The stress measurement method according to claim 1, characterized by the feature.

4. A program that causes a computer to perform a function to set the measurement value correction formula used in the stress measurement method described in claim 1, A representative stress calculation process is performed to calculate a stress-specific test stress, which is a representative value of the test stress in a given stress state, from a plurality of test stresses obtained as a result of repeatedly performing the X-ray test measurement process on the steel sample subjected to the same stress state. The system includes a function to cause the computer to perform a regression equation based on a plurality of stress-specific test stresses obtained as a result of performing the X-ray test measurement process on the steel material sample subjected to different stress conditions, and the logical stress, and a measurement value correction formula setting process based on the regression equation, wherein the computer performs a measurement value correction formula setting process, The representative stress calculation process calculates the stress-specific test stress using an estimation formula based on the average value, standard deviation, and sample size of multiple test stresses related to the same stress state. The measurement value correction formula setting process sets up a stress coordinate system with the logical stress as the first axis and the test stress as the second axis, and sets up the regression formula based on the combination of the logical stress and the test stress for each stress arranged in the stress coordinate system. A measurement value correction formula setting program characterized by the following:

5. The system further includes a function to cause the computer to perform a limit stress selection process to select the limit stress, In the critical stress selection process, stress coordinates consisting of the logical stress and the stress-specific test stress are placed in the stress coordinate system, adjacent stress coordinates are connected to generate line segments, and the critical stress is selected based on the intersection angle formed by adjacent line segments. In the measurement value correction formula setting process, two or more types of regression equations are set with the critical stress as the boundary, and the measurement value correction formula is set based on each of the regression equations. The measurement value correction formula setting program according to claim 4.

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