scholarly journals Investigation of Bonding Behavior of FRP and Steel Bars in Self-Compacting Concrete Structures Using Acoustic Emission Method

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 159 ◽  
Author(s):  
Bo Di ◽  
Jingkai Wang ◽  
Haotian Li ◽  
Jinhang Zheng ◽  
Yu Zheng ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Self Compacting Concrete ◽  
Fiber Volume ◽  
Pull Out ◽  
Steel Bar ◽  
Initial Location ◽  
Steel Bars ◽  
Ae Signal ◽  
Ae Location ◽  
Debonding Process

To extend understanding of the bonding behavior of fiber reinforced polymer (FRP) and steel bars in self-compacting concrete (SCC), an experimental series consisting of 36 direct pull-out tests monitored by acoustic emission (AE) were performed in this paper. The test variables involved rebar type, bar diameter, embedded length, and polypropylene (PP) fiber volume content. For each test, the pull-out force and free end slip were continuously measured and compared with the corresponding AE signals. It was found that the proposed AE method was effective in detecting the debonding process between the FRP/steel bars and the hosting concrete. The AE signal strength exhibited a good correlation with the actual bond stress-slip relationship measured in each specimen. Based on the AE location technique, the invisible non-uniform distribution of bonding stress along the bar was further revealed, the initial location of damage and the debonding process were captured. Additionally, the contribution of bar-to-concrete load-bearing mechanism (chemical adhesion, friction, and mechanical interlocking) to sustain the pull-out force was effectively clarified by studying the collected signals in the frequency domain of AE methods. The experimental results demonstrate that the proposed AE method has potential to detect the debonding damage of FRP/steel bar reinforced SCC structures accurately.

The Analysis of the Reliability and Design for Mechanical Anchorage of HRB500 Steel Bars

2011 ◽  
Vol 94-96 ◽  
pp. 970-974
Author(s):  
Xian Rong ◽  
Peng Cheng Liu ◽  
Xue Li
Keyword(s):  
Concrete Strength ◽  
Concrete Cover ◽  
Statistical Regression ◽  
Analysis Method ◽  
Anchorage Length ◽  
Pull Out ◽  
Steel Bar ◽  
Steel Bars ◽  
Mechanical Anchoring ◽  
Cover Thickness

The factors on mechanical anchoring performance of HRB500 steel bars, such as concrete strength, concrete cover thickness, diameter of steel bar, anchorage length of steel bar and transverse reinforcement ratio, were studied based on pull-out tests of 45 specimens. And the formula of mechanical anchoring bond strength for HRB500 steel bars was concluded by statistical regression analysis method. Through the reliability analysis, the mechanical anchoring length of design value and the table of conversion ratio between mechanical and direct anchoring length of HRB500 steel bars have been proposed. So it could be used as a basis for practical projects. The results indicate that the mechanical anchorage length of HRB500 steel bars can be still designed with the formula proposed in GB 50010-2002 “Code for design of concrete structures”.

Using Acoustic Emission Monitoring to Observe the De-Bonding Behavior of Rebar in Cyclic Pull-Out Tests

2015 ◽  
Vol 784 ◽  
pp. 377-384
Author(s):  
Kuang Chih Pei ◽  
Yu Cheng Kan
Keyword(s):  
Acoustic Emission ◽  
Cyclic Load ◽  
Acoustic Emissions ◽  
Remaining Life ◽  
Bond Behavior ◽  
Signal Density ◽  
Pull Out ◽  
Emission Monitoring ◽  
Rc Structure ◽  
Ae Signal

This research aimed to reveal the bond behavior and failure mechanism of varying size rebar embedded in concrete with inside pre-crack through a series of quasi-static/cyclic pull-out tests and real-time acoustic emissions monitoring (AE). The obtained AE signal density records of the tests provide potential usage for evaluate the safety of reinforced concrete (RC) structure subjected to cyclic load, as well as quantitative study in the remaining life of RC after earthquake or shake damage.

scholarly journals Monitoring of Epoxy-Grouted Bonding Strength Development between an Anchored Steel Bar and Concrete Using PZT-Enabled Active Sensing

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2096 ◽  
Author(s):  
Jian Jiang ◽  
Chuang Hei ◽  
Qian Feng ◽  
Jinwei Jiang
Keyword(s):  
Lead Zirconate Titanate ◽  
Bonding Strength ◽  
Concrete Beams ◽  
Wavelet Packet ◽  
Concrete Specimen ◽  
Strength Development ◽  
Active Sensing ◽  
Pull Out ◽  
Steel Bar ◽  
Steel Bars

Anchored steel bars have been widely used in retrofitting of existing concrete structures. The bonding strength between the anchored steel bar and the concrete is critical to the integrity of the strengthened concrete structure. This paper presents a method to monitor epoxy-grouted bonding strength development by using a piezoceramic-enabled active sensing technique. One concrete beam with an anchored steel bar was involved in the monitoring test, and two concrete beams with six anchored steel bars were used in the pull-out test. To enable the active sensing, a Lead Zirconate Titanate (PZT) patch was bonded to the surface of the exposed end, and piezoceramic smart aggregates were embedded in each concrete specimen. During the monitoring experiment, signals from PZT sensors and smart aggregates were acquired at intervals of 0, 20, 40, 60, 80, and 100 min. In addition, a pull-out test was performed on each of the remaining six anchored steel bars in the two concrete beams, while the signal was recorded in the test. Furthermore, a wavelet packet analysis was applied to analyze the received signal energies to investigate the bonding strength development between the concrete and the anchored steel bar during the epoxy solidification process. The test results demonstrate the effectiveness of the proposed method in monitoring the bonding strength development between the anchored steel bar and the concrete, using the PZT-enabled active sensing.

Correlation Between Acoustic Emission and Wear of Multi-Layer Ceramic Coated Carbide Tools

1997 ◽  
Vol 119 (2) ◽  
pp. 238-246 ◽  
Author(s):  
S.-S. Cho ◽  
K. Komvopoulos
Keyword(s):  
Acoustic Emission ◽  
Cutting Speed ◽  
Shear Zones ◽  
Machining Process ◽  
Contact Friction ◽  
Depth Of Cut ◽  
Near Surface ◽  
Pull Out ◽  
Ae Signal ◽  
Coated Carbide

Acoustic emission (AE) was used to monitor the machining process and tool condition during turning of AISI 4340 steel with uncoated, two-layer (TiC/Al2O3) coated, and three-layer (TiC/Al2O3/TiN) coated cemented WC-Co tools. The experiments were performed at four different feedrates and constant cutting speed and depth of cut. The variation of the AE signal with cutting time is interpreted in light of the dominant mechanisms, rates, and patterns of wear and the contact friction conditions at the tool/workpiece and tool/chip interfaces. Correlations between intrinsic frequencies and AE sources are identified by examining the root-mean-square, dominant amplitude, type, and count rate of the AE signals. It is shown that AE frequencies in the range of 50–100 kHz are primarily due to plastic deformation in the near-surface tool regions and the primary, secondary, and tertiary shear zones of the workpiece, whereas cracking leading to coating delamination and WC grain pull-out generates frequencies in the range of 170–200 kHz. The tool life estimated from the root-meansquare of the AE signal is shown to be in good agreement with that determined from measurements of the maximum wearland width on the tool nose. The obtained results demonstrate that AE is an effective technique for in-process wear monitoring and wear mechanism identification of multi-layer ceramic coated tools.

Bond Behaviors between Polymer Cement Coated Steel Bar Subjected to Environmental Action and Concrete

2016 ◽  
Vol 711 ◽  
pp. 1105-1110
Author(s):  
Yuan Liang Xiong ◽  
Kun Rong Wang ◽  
Zhi Yong Liu
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Failure Modes ◽  
Environmental Action ◽  
Chloride Ingress ◽  
Coated Steel ◽  
Pull Out ◽  
Uncoated Steel ◽  
Steel Bar ◽  
Steel Bars

The bond behaviors (failure modes, bond strength, bond stress slip curves) between steel bars coated with polymer modified cement-based coating and concrete as well as effect of carbonation and chloride ingress on the bond behaviors were studied in this paper. Twenty-four concentrically reinforced concrete cubes were cast and pull-out tests under monotonic loading were carried out. The results indicated that the polymer modified cement-based coating can be well bonded with steel bar and the failure mode of all the specimens is splitting. The typical polymer cement-based coating could enhance the bond strength slightly of the uncoated steel bar with concrete in this experiments. But the bond strength were all depressed between the coated steel bars subjected to carbonation and chloride ingress and concrete.

scholarly journals Study on Acoustic Emission Localization of Concrete Using Modified Velocity

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jiapeng Li ◽  
Lei Qin
Keyword(s):  
Acoustic Emission ◽  
Wave Velocity ◽  
Source Localization ◽  
Wave Speed ◽  
Localization Algorithm ◽  
Measured Velocity ◽  
3D Localization ◽  
Before And After ◽  
Ae Signal ◽  
Ae Location

To improve the accuracy of the acoustic emission (AE) source localization, a new 3D AE source localization method was investigated which used a combination of the modified velocity and the 3D localization algorithm based on the exhaustive method. The wave speed has a significant effect on the AE location results. With the increase of distance, the AE signal seriously attenuated due to the anisotropy of concrete, and the measured velocity changed for various distances. The velocity-distance curves were obtained when employing different water-cement ratios (W/C) and aggregate sizes. However, the current AE location system adopted constant wave velocity. As a result, the error was tremendous. The accuracy of the localization before and after the modified velocity was compared. The 3D localization results showed that compared with the constant wave velocity, the position deviation of the modified velocity was smaller and the localization results with the modified velocity were more accurate.

scholarly journals Analysis of Acoustic Emission (AE) Signals for Quality Monitoring of Laser Lap Microwelding

2021 ◽  
Vol 11 (15) ◽  
pp. 7045
Author(s):  
Ming-Chyuan Lu ◽  
Shean-Juinn Chiou ◽  
Bo-Si Kuo ◽  
Ming-Zong Chen
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Frequency Domain ◽  
Monitoring System ◽  
Welding Quality ◽  
Steel Sheets ◽  
Signal Features ◽  
Ae Signal ◽  
Laser Microwelding ◽  
Ae Signals

In this study, the correlation between welding quality and features of acoustic emission (AE) signals collected during laser microwelding of stainless-steel sheets was analyzed. The performance of selected AE features for detecting low joint bonding strength was tested using a developed monitoring system. To obtain the AE signal for analysis and develop the monitoring system, lap welding experiments were conducted on a laser microwelding platform with an attached AE sensor. A gap between the two layers of stainless-steel sheets was simulated using clamp force, a pressing bar, and a thin piece of paper. After the collection of raw signals from the AE sensor, the correlations of welding quality with the time and frequency domain features of the AE signals were analyzed by segmenting the signals into ten 1 ms intervals. After selection of appropriate AE signal features based on a scatter index, a hidden Markov model (HMM) classifier was employed to evaluate the performance of the selected features. Three AE signal features, namely the root mean square (RMS) of the AE signal, gradient of the first 1 ms of AE signals, and 300 kHz frequency feature, were closely related to the quality variation caused by the gap between the two layers of stainless-steel sheets. Classification accuracy of 100% was obtained using the HMM classifier with the gradient of the signal from the first 1 ms interval and with the combination of the 300 kHz frequency domain signal and the RMS of the signal from the first 1 ms interval.

scholarly journals The duration-energy-size enigma for acoustic emission

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Blai Casals ◽  
Karin A. Dahmen ◽  
Boyuan Gou ◽  
Spencer Rooke ◽  
Ekhard K. H. Salje
Keyword(s):  
Acoustic Emission ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maximum Amplitude ◽  
Time Profile ◽  
Power Law Distribution ◽  
Model Predictions ◽  
Ae Signal ◽  
Strain Signal ◽  
Better Than

AbstractAcoustic emission (AE) measurements of avalanches in different systems, such as domain movements in ferroics or the collapse of voids in porous materials, cannot be compared with model predictions without a detailed analysis of the AE process. In particular, most AE experiments scale the avalanche energy E, maximum amplitude Amax and duration D as E ~ Amaxx and Amax ~ Dχ with x = 2 and a poorly defined power law distribution for the duration. In contrast, simple mean field theory (MFT) predicts that x = 3 and χ = 2. The disagreement is due to details of the AE measurements: the initial acoustic strain signal of an avalanche is modified by the propagation of the acoustic wave, which is then measured by the detector. We demonstrate, by simple model simulations, that typical avalanches follow the observed AE results with x = 2 and ‘half-moon’ shapes for the cross-correlation. Furthermore, the size S of an avalanche does not always scale as the square of the maximum AE avalanche amplitude Amax as predicted by MFT but scales linearly S ~ Amax. We propose that the AE rise time reflects the atomistic avalanche time profile better than the duration of the AE signal.

scholarly journals Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

2019 ◽  
Vol 9 (23) ◽  
pp. 5109 ◽  
Author(s):  
Miguel C. S. Nepomuceno ◽  
Luís F. A. Bernardo
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Surface Hardness ◽  
Pulse Velocity ◽  
Concrete Compressive Strength ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Pull Out ◽  
Concrete Maturity ◽  
Non Destructive

Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.

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