Concrete Infill Monitoring in Concrete-Filled FRP Tubes Using a PZT-Based Ultrasonic Time-of-Flight Method

Abstract

Concrete-filled fiber-reinforced polymer tubes (CFFTs) have attracted interest for their structural applications in corrosive environments. However, a weak interfacial strength between the fiber-reinforced polymer (FRP) tube and the concrete infill may develop due to concrete shrinkage and inadequate concrete compaction during concrete casting, which will destroy the confinement effect and thereby reduce the load bearing capacity of a CFFT. In this paper, the lead zirconate titanate (PZT)-based ultrasonic time-of-flight (TOF) method was adopted to assess the concrete infill condition of CFFTs. The basic idea of this method is that the velocity of the ultrasonic wave propagation in the FRP material is about half of that in concrete material. Any voids or debonding created along the interface between the FRP tube and the concrete will delay the arrival time between the pairs of PZT transducers. A comparison of the arrival times of the PZT pairs between the intact and the defected CFFT was made to assess the severity of the voids or the debonding. The feasibility of the methodology was analyzed using a finite-difference time-domain-based numerical simulation. Experiments were setup to validate the numerical results, which showed good agreement with the numerical findings. The results showed that the ultrasonic time-of-flight method is able to detect the concrete infill condition of CFFTs.

Study on Seismic Performance and Damage Analysis of Steel Plate Shear Wall with Partially Encased Composite (PEC) Columns

“…A PZT tranducer has the unique dual actuating and sensing functions along with its advantage of wide bandwidth, and therefore a PZT tranducer has the ability to generate and detect stress waves [51][52][53][54], including ultrasonic waves [55,56]. As the enanbling element for the active sensing method [57][58][59] and the electromechanial impedance (EMI) method [60,61], PZT transducers are often used in structural health monitoring (SHM) systems [62][63][64][65][66]. With the recent development of PZT based smart aggregates in concrete structure damage detection [67][68][69][70][71] and the application of PZT transducers in health monitoring of steel-concrete composite structures [72][73][74][75], the authors will explore health monitoring and damage detection of steel plate shear wall with PEC Columns using the embeddable smart aggregates [76,77] and the easy-to-install surface-bonded piezoceramic patch transducers [78] in the future work.…”

Residual Axial Bearing Capacity of Concrete-Filled Circular Steel Tubular Columns (CFCSTCs) after Transverse Impact

“…Attention also has been paid to Concrete Filled Fiber Reinforced Polymer (FRP) Tubes, in view of their anti-corrosion properties, which can be better adapted to corrosive environments than CFST [11][12][13][14][15][16]. However, compared with concrete filled FRP Tubes (CFFT), CFSTs are preferred when involving transverse impacts, because steel has much better toughness than FRP when subjected to direct impacts.…”

Damage Analyses of Replaceable Links in Eccentrically Braced Frame (EBF) Subject to Cyclic Loading

“…PZT transducers have other advantages, such as wide bandwidth [63][64][65][66], fast response, and low cost. Therefore, PZT transducers are often be used to generate and detect stress waves in an SHM system [67][68][69][70].…”