The Experimental Research On The Working Stress Measurement Of Concrete By The Ring-Hole Method

The measurement of working stress is to measure the actual stress in a working structure component. The actual working stress of the concrete structure is one of the important indexes which reflect structure state, and it is one of the important parameters for building alteration and strengthened. So, the measurement of the actual stress in the concrete structure is particularly important.In civil engineering, the measurement of working stress is mainly applied in the steel structure. Because of the characteristic of the concrete material itself, how to measure the working stress of concrete accurately is a very difficult problem in the actual project at all times. Though a lot of scholars are researching on this aspect, it is still a brand-new research field. At present, the methods studied most are the ring-hole method, the blind-hole method and the holed drilling method.On the basis of finite element analysis, 5 concrete columns were made to carry on the experimental study about the measurement of working stress of concrete by the ring-hole method. And the problems which might appear in the experiments were discussed;a kind of simple and convenient, practical and reliable method was expected to find out to measure the actual work stress in concrete structure. The paper mainly includes the following contents:1. The release of stress on the measurement point was analyzed by the finite element software ANSYS while the diameter of holing was 100mm. The results indicate that when the hole depth was 33mm, the stress on the concrete surface can be released to zero.2. The strain variations were analyzed with the change of hole depth at the same time by the ANSYS under different hole diameters. Then the release of stress on the measurement point was analyzed under thedifferent load situations. The results indicate that the larger the aperture was;the depth of holing was deeper in which the stress would release to zero. And the stress release did not be influenced by the load on the component.3. The curves of stress-depth of holing were drawed after the experimental studies of 2 concrete columns were done, and the diameter of holing in studies was 100mm. The results indicate that while hole depth was 33mm, strain reading was not zero because the influence of other factors. But strain reading would drop to a smaller value in the course of holing.4. The experimental studies of 3 concrete columns were finished, and then the stress release situations on the concrete surface were specific analyzed while the depth of holing actually for 33mm and 50mm respectively, and the diameter of holing in study was 100mm too. The results indicate that, if 33mm was regarded as the depth of holing, the error of the test results was greater;and if 50mm was regarded as the depth of holing, the error of the test results was less.5. The influence factors on the measurement results of working stress of concrete columns were analyzed, and it was found that the temperature, the water and the vibration were the main influence factors on measurement results.