Research On Structure Condition Assessment Of Concrete Beams Based On Appearance Features Information

As structural damage and failure of the existing RC structure is becoming increasingly acute in the actual project, the structural damage detection and performance evaluation has become the focus of civil engineers. In this paper, based on appearance features of existing RC structure, a series of research work was carried out on structure condition assessment, in accordance with the project (No.50878211) based on National Natural Science Foundation of China. Main work that has been completed is as follow:1. The relation model of deflection of non-cracking beam at the mid-span f and section moment M and the calculation formula of cracking moment were established respectively so as to achieve the load condition assessment of simply supported beam.2. The relation model of the appearance features information of normal section cracks (such as crack width ω and crack spacing l) and mid-span moment M and the calculation formula of flexural capacity Mu were established respectively so as to achieve condition assessment of simply supported beam in bending through appearance features information of normal section cracks.3. The calculation model of the appearance features information of oblique section cracks (such as the inclination of oblique section cracks θ) and shearing capacity Vu was established, and in the meantime Vu and the shearing force V deduced from the mid-span moment M were compared and analyzed so as to achieve the load condition assessment of simply supported beam.4. Through loading experiment which simulates the appearing cracks on the beam, the experimental results and the assessment results based on appearance features information were compared and analyzed. The conclusion shows that calculation results and the experimental results meet.5. In the basement of Visual C++6.0development environments, a system for structure condition evaluation mentioned above is developed by using C++language and MFC class library and the object-oriented programming method.6. The distribution of cracks on the experimental beams was analyzed by using the fractal theory, and the result shows that the distribution agrees the statistical fractal, and there is a relatively good relation between the fractal characteristics and the performance of specimen. Therefore the fractal dimension can be used to describe the development status of the cracks on the concrete beam and the fractal characteristics can be used to assess the condition of the concrete beam.