Analysis Of Influencing Factors Of Ultrasonic Testing Of Simple Stress Field Of Reinforced Concrete Beams

At present,the ultrasonic tail wave testing technology of concrete stress has attracted more and more attention from domestic and foreign researchers.The research object has expanded from a standard test block under a uniaxial uniform stress field to a multiaxial smooth stress field component.The basic research purpose is Establish the functional relationship between coda parameter index and concrete stress.This article takes the “Analysis of Ultrasonic Coda Wave Time Signal Parameters under Eccentric Compression Stress Field” in the National Natural Science Foundation of China(Approval No.51478072)as the research content,and takes the reinforced concrete I-beam as the research object,based on the singular value decomposition The data processing algorithm proposes an experimental technical route that uses ultrasonic amplitude eigenvectors to characterize stress changes.Through the analysis of ultrasonic parameters,coupling agents,temperature and humidity,and other factors,the design and implementation of a reinforced concrete I-beam under eccentric compression under a specific load mode The ultrasonic tail wave test and test plan establishes a linear fitting relationship between the ultrasonic tail wave signal and the load level.The main research contents are as follows:(1)Based on the results of domestic and foreign literature research,the research route of this article is proposed.Focus on investigating the research results of ultrasonic coda waves on the stress testing of concrete structures,and collate,summarize and analyze the principles,methods,test plans and results of relevant research at home and abroad,combined with the ultrasonic coda waves of the research group based on Taylor series and singular value decomposition Based on the test and analysis results,the experimental technical route to characterize stress changes using ultrasonic amplitude eigenvectors is proposed.(2)Build an ultrasonic test and test platform,and design and implement an ultrasonic coda test and test plan for a reinforced concrete I-beam under an eccentric compression load mode In order to ensure the good development of the ultrasonic coda and the stability of the waveform,the reasonable value range of the test equipment parameters is first discussed,such as: transmission pulse width,transmission voltage,trigger delay,sampling frequency and other parameters;second,the ultrasonic coda test The experiment carried out the comparison test of the coupling agent.Finally,the effects of the ambient temperature and humidity,the temperature of the beam and the transducer,and the operating temperature of the ultrasonic instrument on the ultrasonic test waveform were discussed.Through the analysis of the ultrasonic instrument parameters,coupling agent,temperature and humidity and other factors,an ultrasonic test platform under a specific load mode of eccentric compression was built,and stability and repeatability tests were carried out and data collection was completed.(3)Analysis of ultrasonic test data.First,this article discusses the relationship between the absolute energy and load of each day of the stability test ultrasonic test data;second,based on the singular value decomposition,the ultrasonic characteristic vector is constructed by the amplitude(energy)acoustic parameters,so that the inner product of the ultrasonic characteristic vector and the ultrasonic shape is Linear function of stress,and analyze the ultrasonic test data system of stability and repeatability test separately to construct the load and stress index function relationship curve and discuss the error of stress retest.