Test Method for Measuring Uniform and Inhomogeneous Constraint Forces of Concrete-filled Steel Tube Columns Using Piezoelectric Films

Abstract

The invention discloses a test method for measuring the uniform and non-uniform binding force of a steel pipe concrete column by using a piezoelectric film. In the present invention, a piezoelectric film with a thickness of only 28 μm is pasted on the inner side of the steel pipe, and a hole is opened at a position 2d to 30d away from the veneer to lead out a piezoelectric signal, where d is the diameter of the hole, so as to avoid stress concentration at the hole position causing measurement Binding force measurement for position is inaccurate. Utilizing the high sensitivity of the piezoelectric film to dynamic stress, the interaction force between the steel pipe and the concrete is measured through the change of the electrical signal between the upper and lower electrodes of the film. The device of the invention will not damage the interface characteristics of the steel pipe and concrete, and the film is thin and easy to place, the test device is simple, the measurement operation is easy, the measurement result is intuitive, the sensitivity is high and the accuracy is high, and the actual measurement of the binding force of the hoop in the whole process of force can be realized , to realize real-time detection of the binding force of the ferrule during construction or service, and to realize real-time monitoring of the safety and health of the structure.

Description

Technical field [0001] The present invention relates to the technical field of ultrasonic non-destructive detection, and more particularly to a test method using a piezoelectric film to measure the uniform and non - uniform binding force of the steel pipe concrete column. Background technique [0002] During the pressurized process, the steel pipe will generate a sleeve constraint for the core concrete, so that the strength and ductility of the concrete have been greatly improved. Therefore, accurately measure the constraint of the steel pipe to the core concrete to master the steel pipe concrete column. Mechanical properties have a vital role. However, due to the steering tube constraints of the core concrete, the sleeve constraints are present on a narrow interface between the steel pipe and the concrete, and the measuring device for ordinary stress strain cannot be installed, and for the square steel pipe, it is still the constraint of the core concrete. In unevenness, multipl...

AI Technical Summary

Problems solved by technology

However, because the hoop binding force of the steel pipe to the core concrete exists on the narrow interface between the steel pipe and the concrete, the ordinary stress-strain measurement device cannot be installed, and for the square steel pipe, its binding effect on the core concrete is still weak. It is inhomogeneous, and it is even more impossible to install multiple measuring devices on the same cross section

Piezoelectric film is light, thin, durable, and can work passively. It is currently widely used in medical sensors, but there is no report on the binding force detection of steel tube concrete.

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