Test method for measuring active and passive hoop forces in frp - confined concrete columns using piezoelectric membranes

Abstract

The invention discloses a test method for measuring active and passive hoop forces of FRP-confined concrete columns by using piezoelectric films. In the present invention, a piezoelectric film with a thickness of only 28 μm is pasted on the core concrete side wall of the FRP confined concrete column, and a wire connected to the piezoelectric film is drawn from the gap between the FRP fiber filaments at a distance of 2d to 10d from the veneer to output piezoelectric signals. d is the diameter of the opening to avoid inaccurate measurement of the hoop force at the measurement position due to stress concentration at the opening position. Utilizing the high sensitivity of piezoelectric film to dynamic stress, the interaction force between FRP and concrete is measured through the change of electrical signal between the upper and lower electrodes of the film. The device of the present invention will not destroy the interface characteristics of FRP 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 accurate, and the actual measurement of the binding force of the hoop during the whole process of force can be realized , to realize real-time detection of the binding force of the hoop during construction or service, and to realize real-time monitoring of the safety and health of the structure.

Description

technical field [0001] The invention relates to the technical field of piezoelectric materials, in particular to a test method for measuring active and passive hoop forces of FRP-confined concrete columns by using piezoelectric films. Background technique [0002] Fiber-reinforced composite (FRP) confined concrete column is a new type of composite column formed by wrapping FRP on the outside of ordinary concrete columns. Since the internal concrete is in a three-dimensional stress state under the constraint of external FRP, the FRP-confined concrete column It has high bearing capacity and good axial ductility. At the same time, the external FRP can protect the internal concrete so that the FRP-confined concrete column has good durability. Therefore, the FRP-confined concrete column is gradually used in engineering repair and reinforcement and new structures. . FRP-confined concrete can be divided into passive confinement and active confinement. Passive confinement is caused...

AI Technical Summary

Problems solved by technology

However, since the binding force between FRP and concrete exists on the interface between FRP and concrete, ordinary stress-strain measurement devices cannot be installed, while piezoelectric films are light, thin, durable and easy to install, and can work passively. It is widely used in medical sensors, but there is no report on the hoop force detection of FRP-confined concrete

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