Damage Identification Of Beam Structure Based On The Theories Of Energy Dissipation And Probability Statistics

Due to the influence of load and environment, beam structures in service would inevitably appear damage accumulation and resistance attenuation, this will impact the safety or durability of structures. Therefore, researching the damage identification of beam structures is of great actual significance.At present, the majority of identification methods are easy to arise misjudges at the symmetric position of actual damage site, and most of the research is processed by the means of numerical simulation, the identification results are lack of experimental verification. This paper conducts numerical analysis and experimental study on the damage identification of simply supported I-beams, based on the theory of energy dissipation and probability statistics, the main contents and corresponding conclusions are as follows:Numerical study based on energy dissipation is conducted on a simply supported I-beam, the results indicate that the method of energy dissipation can locate the damage position exactly and evaluates the level relatively, but does not apply to identify the damage of mounts.Experimental study is carried on the damage identification of simply supported I-beam, and the damage of test beams is made by cutting cracks on the bottom flange, then the index of natural frequency and element damage variable are used to identify the preset damage separately. The results indicate that natural frequency can only identify the emergence of damage, excluding the damage position, and it is insensitive to the little damage, the biggest decline rate of natural frequency caused by2mm crack for two test beams is0.06%and0.08%respectively. The method of energy dissipation can locate the2mm and4mm crack of test beams, and represent the damage level relatively.In order to inspect the identification precision of energy dissipation method under noise, measurement noise is added to the modal data obtained from numerical simulation. The results indicate that the identification precision of energy dissipation method is reduced with the increase of noise level, and this method is unable to identify30%damage under2%noises.Combined the method of energy dissipation and probability statistics, and using the mode data with noise to identify the damage of simply supported I-beam in statistical mode. The results indicate that the identification precision of statistical method is improved obviously contrast with deterministic method. The deterministic method is unable to identify the damage of the beam under2%noises, however, the statistical method can identify10%damage with fifty samples under3%noises.