Experimental Study Of The Working Stress State Of Concrete Frame Structures Through Ultrasonic Testing

The structural work stress is an important index for evaluating the safety performance of existing buildings,and the method is mostly a damage detection to the detection of concrete work stress,which not only causes secondary “injury” to the actual building,but also changes the original stress state to a certain extent.Ultrasonic non-destructive testing methods have been widely recognized in practical engineering because of their convenient operation and accurate detection.In this paper,the ultrasonic sound velocity and amplitude of the ultrasonic wave are used to detect the variations of the ultrasonic velocity and the amplitude of ultrasonic wave in the basic components of the beam and column structure.The reliability theory is used to determine the index of structural damage,and the corresponding relationship between stress and sound velocity is established to provide the concrete engineering test.This article specifically carried out the following aspects of the study:Through ultrasonic testing of concrete beams,the variation of ultrasonic parameters at different positions of beams under different loads is studied,and the influence of ultrasonic velocity variations on the ultrasonic wave velocity in the bending zone,tension zone and shear zone in the pure bending zone under working stress is analyzed.The study shows that the sound speed variation in the tension zone is greater than that in the compression zone of the purely curved section of the concrete beam,while the sound speed of all measurement points in the shear bending segment is basically unchanged.Through ultrasonic testing of concrete column members the effect of different loading rates on the variation of ultrasonic sound velocity of concrete columns under stress is studied.The study shows that the smaller the hoop rate is,the earlier the sound velocity will decrease.And with the increase of the hoop rate,the effect is less obvious.Through ultrasonic testing of concrete frames,the influences of the variations of the sound velocity and amplitude at different positions of frame beams and frame columns under working stress and the internal relations between them are studied.The ultrasonic sound velocity of the concrete components and structures is analyzed and compared.The law of value change.The research shows that the change trend of sound velocity of concrete frame structures is basically the same as the concrete components.However,compared with concrete components,the ultrasonic sound velocity and stress of concrete structures tend to change more slowly,and the sound velocity value also decreases even more;the ultrasonic amplitude of concrete frame structures and the stress correspondence relationship has no regularity,and it is not appropriate to use the amplitude to detect and evaluate the working stress of the concrete structure.Based on the experiment,the relationship between the stress of the concrete frame structure and the ultrasonic speed of sound is established,and the coefficient table suitable for different positions of the concrete frame is given.In the practice engineering,this curve can be used to initially detect the stress state of the structure and provide references for testing and evaluation.The reliability of the structural safety is calculated by the reliability theory,and the structure is regarded as a tandem system.It is divided into three parts: the compression of the concrete column,the bending of the normal section of the concrete beam and the shear of the oblique section.The reliability of the method is analyzed by checking point method,and the index of structural damage degree is determined.