Test method for measuring active and passive hooping forces of FRP confined concrete column by adopting piezoelectric film

Abstract

The invention discloses a test method for measuring active and passive hooping forces of an FRP confined concrete column by adopting a piezoelectric film. According to the invention, the piezoelectricfilm with the thickness of only 28 [mu]m is pasted on the side wall of the core concrete of the FRP confined concrete column, wires connected with the piezoelectric film are led out from the gaps ofFRP fiber filaments at the position 2 d to 10 d away from the attaching face so as to output piezoelectric signals, and d is the diameter of the open hole so as to avoid inaccurate measurement of thehooping force at the measurement position caused by stress concentration at the open hole position. The high sensitivity of the piezoelectric film to dynamic stress is utilized, and the interaction force between FRP and concrete is measured through the change of an electric signal between an upper electrode and a lower electrode of the film. According to the device, the interface characteristics of the FRP and the concrete are not damaged, and the film is thin and easy to place; and the testing device is simple, the measurement operation is easy to implement, the measurement result is visual,the sensitivity and accuracy are high, the actual measurement of the hoop constraint force in the whole stress process can be realized, the real-time detection of the hoop constraint force in the construction or service process is realized, and the real-time monitoring of the safety and health of the structure can be realized.

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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