System and method for in-situ detection of prestressed structures in service

Abstract

The invention discloses an in-service structure prestress in-situ detecting system and method. The detecting system comprises an adjustable signal source unit, a high-input impedance unit, an A / D switching circuit, a voltage testing processing display unit, a system parameter input unit, an impedance matching unit and an amplification unit. According to the system, a reinforcing steel bar is used as a conductor with an input end and an open-circuit terminal end, electromagnetic waves can be reflected on the terminal to form a standing wave, forming of the standing wave is directly related with the propagation characteristics of the electromagnetic waves in the reinforcing steel bar, the propagation characteristics are directly associated with the magnetic conductivity of the reinforcing steel bar, and the magnetic conductivity of the reinforcing steel bar changes along with the stress, so that voltage changes of electromagnetic waves residing in an endpoint are directly associated with the stress changes of the reinforcing steel bar, and are spread through a plurality of wave lengths in the reinforcing steel bar, the voltage changes of the standing wave can be amplified, finally the size of stress can be directly displayed on the voltage changes of the standing wave of the open-circuit terminal, the electrochemical expression of the absolute stress is achieved, and due to the detection of the voltage, the absolute stress borne by the reinforcing steel bar can be directly obtained.

Description

technical field [0001] The invention relates to the field of stress detection of steel bars, in particular to an in-situ detection system and method for in-service structural prestress based on the transmission characteristics of slow electromagnetic waves in single-wire ferromagnetic materials. Background technique [0002] The prestressed structure has the advantages of good performance and light weight, and has become the first choice for building structures such as bridges and dams. The load-bearing capacity of prestressed beams determines the service life of these structures. At the same time, prestress is also the internal driving force of externalized damage. For example, due to changes in internal stress, bridges crack, deflection increases, or even break and collapse. Real-time detection of steel bars in bridges and other structures The internal stress of the bridge becomes particularly important. It can specifically understand and monitor its internal prestress los...

AI Technical Summary

Problems solved by technology

Concerning the magnetic nondestructive testing of damage and stress of ferromagnetic components, credible research results have been obtained, but these researches are concentrated in the fields of aerospace, machinery, petroleum, etc., mainly for the magnetic detection of damage and stress of ferromagnetic components of homogeneous steel structures. Non-destructive qualitative testing, and in the fields of civil engineering and bridge engineering, there is little research on electromagnetic non-destructive testing for the overall damage and internal force distribution of multi-strand steel strands; in addition, the current cables tend to use steel protective sleeves, so that the magnetic field penetration becomes less poor, the test effect deteriorates; at the same time, this method cannot be used for the stress of the steel bars in the concrete prestressed steel beams because the volume is too large to load the magnetic selection; again, for the stress test of the in-service pre-structure, because the structure has been installed in the specified position, the magnetic coil also cannot be loaded and cannot be used

Images