Study On Prestressed Nondestructive Testing Technology Of Continuous Rigid Frame Bridge Based On Magneto-elastic Method

With the rapid development of bridge construction, we have witnessed the growing number of in-service or on-building long-span prestressed concrete continuous rigid frame bridge. But among the in-service long-span prestressed concrete continuous rigid frame bridges, excessivemid-span deflection problem is increasingly prominent, which directly affects the driving safety and comfort. The current consensus of the reason is the excessive longitudinal prestress loss. However, the factors that caused the prestress loss are varies and affecting each other, which make it complicated and difficult to accurately calculate the total prestress loss. People have successively joined the study about prestress loss detection method. Now there are many nondestructive testing methods to detect the effective prestress, but what can be used in practical engineering with high precision, strong anti-interference ability and high stability are rare. Therefore, this paper mainly focuses on the study on prestressed nondestructive testing technology of continuous rigid frame bridge based on the Magneto-elastic Method. Through putting forward testing application technology and verifying the reliability and applicability of the Magneto-elastic Method used to test the effective prestress of continuous rigid frame bridge, we can provide some basis for further research and practical application on prestressed detection method. The main contents of the paper include:①Based on the introduction of the principle of the Magneto-elastic Method, the paper takes some research about the design, guidelines and the mechanism of the influence of temperature and temperature correction method of the magnetic flux sensor based on prestressed continuous rigid frame bridge.②The paper takes many analysis of the Magneto-elastic Method for detecting the effective prestress of continuous rigid frame bridge, including the placement technology for magnetic flux sensor, the installation technology, the scene detection technology as well as the factors affecting the detection accuracy and the solutions.③Relying on practical engineering, the paper uses the magnetic flux sensor to test the effective prestress of testing steel beam during prestressed tension stage of Niulanjiang bridge in Zhaotong city, Yunnan province. Then selects the roof beam and web beam to test the pipe friction, and analyzes the variation of pipe friction coefficient during prestressed tension stage. And then provides the reasonable value range of ? 、k and the recommended correction formula of the friction loss.④According to the 04 specification, calculate the prestress loss of testing steel beam during the construction period. Establish the Midas Civil finite element model, and then assign the model with specified value of 04 specification and the measuring value of the friction coefficient. And then compare the measuring value and the calculated value and the model value to get the basic laws of prestress loss and some related conclusions. Then verify the reliability and applicability of the Magneto-elastic Method for detecting the effective prestress of continuous rigid frame bridge.