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.

scholarly journals Real-Time Monitoring of Timber-Surface Crack Repair Using Piezoelectric Ceramics

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Huien Meng ◽  
Wenwei Yang ◽  
Xia Yang
Keyword(s):  
Real Time ◽  
Lead Zirconate Titanate ◽  
Surface Crack ◽  
Wavelet Packet ◽  
Damage Index ◽  
Piezoelectric Ceramics ◽  
Strength Development ◽  
Active Sensing ◽  
Surface Cracks ◽  
Crack Repair

Real-time assessment of timber-surface crack repair is crucial to the stability and safety of timber structures. Epoxy resin was used to repair timber cracks, and the active sensing technique using piezoelectric ceramics was applied to monitor the repair process of timber surface cracks in real time. Sixteen wood samples were designed for axial compression tests and active monitoring tests. A pair of lead zirconate titanate patches was pasted on the surface of the timber specimens as actuators and sensors for signal transmission and reception, through wavelet packet analysis, the variations in the signal amplitude, and wavelet coefficients. The relationship between the wavelet packet energy of the monitoring signal and the ultimate bearing capacity of the specimens at different periods after grouting was established. Based on the root-mean-square deviation, the damage index, DI, was introduced to evaluate the repair degree of timber surface cracks quantitatively. The results showed that the active sensing method can evaluate the strength development in timber-surface crack repair in real time.

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”.

scholarly journals Experimental Study of Replacement the Tension Reinforcing Bars in Concrete Beams by Steel Pipes

2018 ◽  
Vol 7 (4.20) ◽  
pp. 229
Author(s):  
Labeeb Saadoon Al-Yassri ◽  
Alaa Mahdi Al-Khekany ◽  
Hajer Satea Abbas
Keyword(s):  
Reinforced Concrete ◽  
Construction Projects ◽  
Concrete Beams ◽  
Small Diameter ◽  
Reinforced Concrete Beams ◽  
Steel Pipe ◽  
Steel Pipes ◽  
Steel Bar ◽  
Steel Bars ◽  
The Difference

Structures designed with reinforced concrete beams are used extensively in construction projects because of their functional and economic features. In this research, tested concrete beams were cast and reinforced with small diameter steel pipes and /or steel bars as flexural reinforcement to study the effect of this configuration of reinforcement on the structural behavior of reinforced concrete beams. The idea of this research involves performing and testing of four reinforced concrete beams reinforced by small diameter steel pipes with different percentages of replacement with traditional steel bars (0%, 33%, 66% and 100%). The experimental results showed that using of steel pipes reduces the flexural capacity by (2.7, 18.3, 37.5%) if compared with traditional steel bar according to the replacement percentages of (33%, 66%, and 100%) respectively. Moreover, the stiffness of beams reinforced with steel pipes (fully or partially) decreased as a result of the difference in the mechanical properties between steel bar and the steel pipe and also, the bond strength reduction between the smooth steel pipe and surrounded concrete.  

Experimental Study and Numerical Simulation of Bond Behaviors Between FRP Bar and Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 2134-2138
Author(s):  
Xin Sheng Xu
Keyword(s):  
Bond Strength ◽  
Shear Failure ◽  
Concrete Specimen ◽  
Screw Thread ◽  
Bond Slip ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Steel Bars ◽  
Frp Bar ◽  
Frp Bars

Surface-adhering-sand screw-thread-form FRP bar was produced. By symmetrical pull-out test research to a certain depth in FRP (Fiber Reinforced Polymer) bar concrete, the bond mechanism, the failure mechanism, the bond strength and the slip of FRP bar to concrete were studied systematically. Studies show that the failure mode is not the damage of the ribs or the shearing off of the ribs, but is shear failure between the screw thread and the core of the FRP bar, and the sands on the surface of the bar were grinded into powder. The descending branch of load-slip curve for the FRP bars is gentler than that for the steel bars. The bond strength of FRP bars is a little lower than that of steel bars, but higher than smooth FRP bar greatly. At last the FRP bar concrete specimen were modeled in ANSYS program and the simulation result is satisfactory, which proves the feasibility to model the behavior of bond-slip relationship between FRP bar and concrete accurately.

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.

Experimental Study on Flexural Bearing Capacity of Reinforced Ceramsite Concrete Beam

2011 ◽  
Vol 366 ◽  
pp. 253-257
Author(s):  
Wei Jun Yang ◽  
Zheng Bo Pi ◽  
Zhen Lin Mo
Keyword(s):  
Bearing Capacity ◽  
Concrete Beam ◽  
Failure Modes ◽  
Concrete Beams ◽  
Cement Mortar ◽  
Reinforced Concrete Beams ◽  
Ordinary Concrete ◽  
Steel Bar ◽  
Steel Bars ◽  
Flexural Bearing Capacity

In order to investigate the flexural bearing capacity of reinforced ceramic concrete beams, static loading experiments were carried out. 10 ceramic reinforced concrete beams and 2 non-reinforced ceramic concrete with different steel ratios, cover thicknesses and bar diameters were fabricated. The gauges of concrete was arraged on the surfaces of section in mid-span and and steel gauges was arraged on the surfaces of steel bars. The loading device was consisted of a 200kN hydraulic jack, a distributive girder and reaction frame while the dial indicators was arraged in supports and mid-span. The strain of concrete and steel bar in different loading along with the crack,yield and utimate of load were recorded .It found that the stress-strain law, crack extension regularity , failure modes of specimens was similar to the ordinary concrete beams and the current procedures formulas about flexural bearing capacity is reliability. It also found that both ceramic aggregate and cement mortar were crushed for the perfectly bonding of the interface and the strength of aggregate was to be fully utilized.

scholarly journals Detecting Debonding between Steel Beam and Reinforcing CFRP Plate Using Active Sensing with Removable PZT-Based Transducers

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 41 ◽  
Author(s):  
Jian Jiang ◽  
Jinwei Jiang ◽  
Xiaowei Deng ◽  
Zifeng Deng
Keyword(s):  
Stress Wave ◽  
Lead Zirconate Titanate ◽  
Wavelet Packet ◽  
Experimental Studies ◽  
Steel Structure ◽  
Steel Structures ◽  
Lead Zirconate ◽  
Steel Beam ◽  
Active Sensing ◽  
Cfrp Plate

Carbon fiber reinforced polymer (CFRP) plates are widely used to retrofit or reinforce steel structures, and the debonding damage between the steel structure and the CFRP plate is a typical failure in strengthening steel structures. This paper proposes a new approach to detecting debonding between a steel beam and a reinforcing CFRP plate by using removable lead zirconate titanate (PZT)-based transducers and active sensing. The removable PZT-based transducers are used to implement the active sensing approach, in which one transducer, as an actuator, is used to generate stress wave, and another transducer, as a sensor, is used to detect the stress wave that propagates across the bonding between the steel beam and the reinforcing CFRP plate. The bonding condition significantly influences the received sensor signal, and a wavelet-packet-based energy index (WPEI) is used to quantify the energy of the received signal to evaluate the severity of debonding between the steel beam and the reinforcing CFRP plate. To validate the proposed approach, experimental studies were performed, and two removable PZT-based transducers were designed and fabricated to detect the debonding between a steel beam and the reinforcing CRFP plate. The experimental results demonstrate the feasibility of the proposed method in detecting the debonding between a steel beam and the reinforcing CFRP plate using removable PZT-based transducers.

scholarly journals Interface Debonding Detection of Precast Segmental Concrete Beams (PSCBs) Using Piezoceramic Transducer-Based Active Sensing Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yang Liu ◽  
Ming Zhang ◽  
Xinfeng Yin ◽  
Chuang Hei ◽  
Lei Wang
Keyword(s):  
Concrete Beams ◽  
Wavelet Packet ◽  
Damage Index ◽  
High Strength ◽  
Frequency Domain Analysis ◽  
Interface Debonding ◽  
Active Sensing ◽  
Periodic Loading ◽  
Debonding Detection ◽  
Epoxy Resin Adhesive

An active sensing approach using piezoceramic induced stress wave is proposed to provide monitoring and early warning for the development of interface debonding damage of precast segmental concrete beams (PSCBs). Three concrete specimens with toothed interfaces were fabricated and bonded with high-strength epoxy resin adhesive to form PSCBs. Smart aggregates (SAs) embedded in concrete specimens are used as actuators and sensors. The PSCBs are subjected to periodic loading with hydraulic jack to test the different degrees of debonding damage. The experimental results of time-domain and frequency-domain analysis clearly show that the amplitude of the signal received by the piezoceramic sensor is reduced when debonding crack occurs. The energy analysis and damage index based on wavelet packet can be used to determine the existence and severity of interface debonding damage in PSCBs. The experimental research validates the feasibility of monitoring the interface debonding damage in PSCBs using SA transducers based on active sensing technique.

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