Methods For Inferring Resistance Of Exiting Structures Based On Non-destructive Test

The prerequisite to evaluate the reliability of existing structures is to infer the resistance of structural member exactly. Currently, the main methods used for inferring the resistance of structural member are the direct inference method based on destructive test and the indirect inference method based on material test. Although the inference results of the direct inference method can reflect the actual resistance of component, this method is inconvenient in practical application and cannot meet the requirements for the existing components to continue to carry the loads. The indirect inference method is easy to implement, but its inference result is too conservative and can't take the actual performance of the resistance of structural member into consideration well. The inference method for resistance under the condition of insufficient test is put forward internationally, which combines the advantages of the direct inference method and the indirect inference method. However, this method can only present the lower limit value of the resistance and can't give the final inference of the actual resistance of component.In addition, this method doesn't consider the uncertainty in inferring and the comprehensive inference method for multiple test specimens.Aiming at the shortcomings of the current resistance inference method, the paper proposed the method for inferring resistance of existing structures based on non-destructive test. First of all, according to the requirements of the non-destructive test, the steady state test way is used for the testing of resistance, namely, one can regard the test is over when the specimen reach the status set advanced. Then, based on the method of stochastic process and the conditional probability, the probability prediction method under the condition of insufficient test for single specimen ultimate resistance is established. Finally, according to the prediction results of the probability of each specimen and the analysis process of full probability method, the small sample inference method of structural members for multiple specimens is proposed. On the basis of the established theoretical method, this method is used into the reinforced concrete flexural members; thus, the inference method of the flexural bearing capacity for flexural members based on non-destructive test is proposed. The result of example analysis show that the proposed method was to use a more comprehensive information of the component itself, and the inference result is more closer to the actual value and has smaller variability.The method for inferring resistance of existing structures based on non-destructive test is a supplement for the inference method of the resistance for existing structures currently.The test involving in this method is non-destructive test. Without causing damage to the component, the method considers the actual performance of resistance,makes up for the lack of the direct inference method and the indirect inference method,improves the resistance inference method under the condition of insufficient test in international and the method has more prominent empirical and targeted. The proposed method expands the application field of structural test, provides design-assisted design method with more empirical for reliability assessment of existing structures, which can more effectively ensure the reliability of the structures, especially significant engineering structures and the new types of structures.