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By considering the application requirements of automatic welding of labels on the heads of bundled rebars in the iron and steel industry, an automatic label welding robot system is developed based on machine vision and image processing. The system consists of six modules: pickup unit, image unit, control unit, welding stud unit, label unit, and rebar unit. It can automatically pick up welding studs, pick up labels, perform welding, detect dropped labels, and detect dropped welding studs. The development process of label welding mainly includes the following steps. First, the Cascade RCNN object detection algorithm is used to detect the rebar head, so that the number of rebars and the pixel coordinates of the rebar head centers can be obtained. The detection accuracy of the number of rebars can reach 100%, and the Cascade RCNN average score is 0.9801. Then, an algorithm to identify the center of bundled rebar heads based on the variable-scale method (Davidon–Fletcher–Powell formula (DFP)) is proposed. In addition, limiting conditions, and a process for selection of weldable points for double-label welding are provided. And the coordinate conversion equations of weldable points in different coordinate systems are derived. Finally, a serious of functional verification tests of the robot system were carried out on an actual rebar production line, which verified the accuracy of the weldable point image recognition process, and the usability of the robot system. The results indicate that the accuracy of weldable point recognition can reach 98.99%.

Load-bearing structural elements such as rock bolts and reinforcing bars (rebar) are ubiquitously present in both mining industries and in infrastructure projects, for securing tunnel walls and ceilings. Being able to detect and localize defects in previously installed rock bolts, or even quantitatively estimate the load they are taking, would be very valuable when planning maintenance and service. Unfortunately, there are no such techniques available today. Previous work shows that ultrasound, being a mechanical wave, is sensitive to mechanical changes in rock bolts. The ultrasound signature is, however, rather complex, and traditional modeling of the wave propagation rapidly becomes challenging. In this paper, we show that the ultrasound signature measured from a 3.2 m long dynamic rock bolt can be used to accurately determine the load applied to the bolt and the resulting elongation of the bolt. The method is based on training a Partial Least Squares Regression (PLSR) model to estimate the force an elongation from power spectra of backscattered ultrasound signatures.

Early and timely detection of bridge surface damage plays a key role to maintaining bridge functionality and guaranteeing transportation safety. The common practice is to detect bridge damage by artificial visual inspection. However, it is time-consuming, labor-intensive and has a low-efficiency. This paper presents a simple, high-accuracy framework to detect four types of bridge damage based on ResNet-101 model. A damage images dataset with 2,726 images including crack, spall, rebar exposed and honeycomb is developed for training and testing the ResNet-101 model. To enhance detection accuracy, a transfer learning method with fully pre-trained weights from a similar dataset was adopted as it improves the original ResNet-101. The robustness and adaptability of the trained ResNet-101 model are tested on test dataset. Result shows that compared with traditional classification models, the proposed approach can effectively detect those four kinds of bridge damage in realistic situations with a better performance.

Ground penetrating radar (GPR) is a recognized nondestructive testing technique, which has been commonly applied to detect the steel bars (rebars) in concrete. However, most commercial GPR systems can only record reflection signals in single polarization, making the inspection of rebar corrosion difficult. In this paper, we employ a full polarization GPR system to record polarimetric information and use H-Alpha polarization decomposition to evaluate the rebar corrosion process. A yearly long corrosion process of one rebar was accelerated within 15 days by applying a constant current density of 0.3 mA/cm2 on the embedded rebar. The preliminary experimental results of polarization decomposition show that the scattering characteristics of rebars change to low entropy surface scattering after corrosion. It is concluded that full-polarimetric GPR has a potential for characterization of the early-stage corrosion of concrete rebar.

This study developed a bi-dimensional model of a steel-reinforced concrete (RC) structure under cathodic protection against corrosion using the Finite Element Model (FEM) based Comsol Multiphysics software. Two small RC samples’ frontal geometry was considered from a reported experimental study, tested here against corrosion in a chloride environment. Those samples had different rebar diameters (10 mm and 16 mm). The reported specific electrochemical parameters and material properties were selected through this numerical investigation. The cathodic protection system’s optimization process was based on identifying the appropriate external applied potential $E_{app}i$ which lowers at minimum the corrosion rate. In this purpose, the first average corrosion current density i Fe under the value with minimum corrosion risk (of 0.1 $\mu A/cm^{2}$) was identified for both models. For Model 1 with rebar diameter of 10 mm, a safe i Fe value of 0.087 $\mu A/cm^{2}$ was attained $E_{app}i=-0.225V$, and for Model 2 with rebar diameter of16 mm, $i_{Fe}=0.085\mu A/cm^{2}$ at $E_{app}i=-0.15$ V.

Ground penetrating radar (GPR) is a well-established tool for detecting and locating reinforcing bars (rebars) in concrete structures. However, using GPR to quantify the diameter of rebars is a challenging problem that current processing approaches fail to tackle. To that extent, we have developed a novel machine learning framework that can estimate the diameter of the investigated rebar within the resolution range of the employed antenna. The suggested approach combines neural networks and a random forest regression and has been trained entirely using synthetic data. Although the training process relied only on numerical training sets, nonetheless, the suggested scheme is successfully evaluated with real data indicating the generalization capabilities of the resulting regression. The only required input of the proposed technique is a single A-scan, avoiding laborious measurement configurations and multisensor approaches. In addition, the results are provided in real time and making this method practical and commercially appealing.

We calculate forward transient scattering by a metal cylinder covered with a homogeneous medium (coated metal cylinder). A time-domain asymptotic-numerical solution (TD-ANS) is used for computations in a forward transient scattered electric field by a coated metal cylinder. An analysis method using the TD-ANS provides a basis of nondestructive testing for corrosion degree of rebar in steel reinforced concrete structures. We confirm the validity of the TD-ANS by comparing with a reference solution. We also discuss an interpretation method of the forward transient scattered electric field using the TD-ANS.

We calculate backward transient scattered electric fields from a coated metal cylinder, which is covered with a homogeneous medium layer. A time-domain asymptotic-numerical solution (TD-ANS) is used for computations in a backward transient scattered electric field by a coated metal cylinder. An analysis method using the TD-ANS provides a basis of nondestructive testing for corrosion degree of rebar in steel reinforced concrete structures. By comparing with a reference solution, we examine an interpretation method of response waveforms of backward transient scattered electric fields by using the TD-ANS.

Construction of residential houses usually faces various issues and problems due to the use of poor quality materials such as the steel reinforcing bar. The steel reinforcement process is an integral factor responsible for resisting tension while the concrete complex is being reinforced. The steel rebar currently used in Duhok governorate are majorly sourced from local manufacturers, with a portion is imported from neighboring countries. The sampling process involved four local rebar brands and an extra three imported (do not permit to disclose their brand names). The 12 mm steel bars were tested on the basis of tensile strength and elongation. The results were established after comparing the recent standard specification codes in British, American, and Iraqi. The results showed the majority of steel brands used in Duhok governorate to meet standards specification. However, there were some differences in some brands with regards to the ultimate strength, elongation, effective diameter, and mass.

Application of corrosion inhibitor has been practiced to counter the development of corrosion in reinforced concrete. However, utilization of corrosion inhibitor may compromise the bond between concrete and steel bar. The study investigated the bond performance of corroded rebar in concrete with corrosion inhibitor using impressed current technique. The relationship of bond strength and corrosion accumulated by reinforcement, non-coated (NC) and coated (C) with corrosion inhibitor are the main variables of this study. Thirty samples were subjected to impressed current technique to accelerate corrosion. For every 7-day interval within a 28-day period, 6 samples (NC and C) were tested using single pull-out test to determine the bond strength. Upon using ANOVA, results demonstrated an increasing trend of corrosion level for samples exposed longer to impressed current, with a P-value of 5.11 e-07. On the other hand, a SLRA derived model for bond strength as a function of corrosion level showed that bond strength of reinforcement (C and NC) decreases by 0.5508 MPa, and 1.2078 MPa respectively. Both models are deemed to be significant having a P-value and Multiple R of 0.0371, 0.5415 and 0.0009, 0.7667, for C and NC respectively.

The objective of this research was to investigate the effects of twisted steel micro-rebar (TSMR) fibers on the early cracking behavior of concrete bridge decks. The methodology for this research involved the evaluation of four newly constructed bridge decks, two that were constructed using conventional concrete and two that were constructed using TSMR. At bridge deck ages of 3 months, 1 year, and 2 years, the extent and severity of any deck surface cracking was documented in terms of crack lengths and widths, respectively. The data were used to create crack maps, and crack density was calculated for each bridge deck. Bridge decks containing TSMR exhibited notably reduced cracking when compared to the conventional decks. The bridge decks containing TSMR also exhibited the ability to limit the expansion of existing cracks. The significant decrease in the amount of cracks and reduced crack widths indicate that the TSMR fibers were successful in mitigating bridge deck cracking.

Steel manufacturing industries take advantage of growing infrastructure market by producing high volumes of rolling products like rebars. However, in the face of competition, better cost effective automation solutions are needed to run rolling mills at a high speed which would guarantee a high return of investment. In this paper, automatic, visual inspection methods are proposed to investigate rebar falling patterns and rebar surface properties at very early stage during the production of rolling stock. We propose a multi-modal adaptive control approach for rolling processes with camera, process, and material data to improve process and quality control in rolling mills.Image processing methods are proposed to detect and identify abnormalities in rolling stock and communicate visual information with a feedback mechanism to a control system and/or a manual operator. The visual information is transformed into sequential data with exponential weighted mean statistics and symbolic aggregate approximation techniques. We demonstrate, on real video streams, deviation statistics and identify set point corrections to improve time to deliver the stock; generate interpretable labels to quantify material loss and identify extent of deficiencies in rolling stock for assistance to manual operators.

Concrete is a nonhomogeneous medium that contains coarse aggregate, sand (fine aggregate), cement powder, water and porosity. Microwave non-destructive testing (NDT) technique is used to simulate three layered media that contains air gap, coarse aggregate and a two layered media that contain rebar and void is modeled as closest to the reality. Interaction of electromagnetic wave and the concrete pile is utilized for numerical simulation. A Finite-Difference Time-Domain (FDTD) method with Perfectly Matched Layer (PML) Absorbing Boundary Condition (ABC) is proposed to simulate electromagnetic wave propagation in FRP tube and composite pile. 2D simulation of a wave generated from a point source at microwave frequencies is obtained by using MATLAB®.

What's the difference between the coil impedance changes induced by the ferromagnetic and nonferromagnetic cylinders? What's the difference between the coil impedance changes induced by the cylinders with different conductivity? It is important to make them clear theoretically. According to the second order vector potential theory, the coil impedance change can be expressed as the function of the coil coefficient and the reflection coefficient when the normal direction of the circular solenoid coil is perpendicular to the axis of the conductive cylinder. It is also a function of lift-off (or cover depth, the least distance to the surface of the concreate), diameter, conductivity of the cylinder and the exciting frequency. Theoretical and experimental results show that the coil reactance change is negative, the coil resistance change is positive, and the magnitude of them increases as the exciting frequency increases if the cylinder is made of nonferromagnetic materials. If the cylinder is made of ferromagnetic materials, the coil reactance change is positive in the lower frequency band, it increases as the frequency increases, and reaches to its maximum at the frequency fx max . After that, it decreases as the frequency increases continuously. At a special frequency fx 0 , the reactance change decreases to zero. When the frequency is higher than fx 0 , the reactance change decreases as the frequency increases continuously, in the other words, the magnitude of the reactance change increases as the frequency increases in the upper frequency band. The coil resistance change induced by ferromagnetic cylinder increases as the frequency increases in the whole frequency band we studied. In the upper frequency band, the impedance changes, which are induced by ferromagnetic and nonferromagnetic cylinders with same conductivity and diameter at the same liftoff, have little difference. The influence of the conductivity of the cylinder on the coil impedance change, and the physical interpretation of the impedance change induced by ferromagnetic cylinders are also studied. These characteristics of the coil impedance change can help to design the nondestructive testing instruments such as the cover meter to locate and evaluate the diameter of the rebar embedded in concreate, and the conductivity testing meter, etc. They can also help the designer to choose exciting frequency and optimize the performance of these nondestructive instruments.

In prefabricated buildings, the compactness of grouting in connection sleeve plays a decisive role in structural safety. However, there is no efficient method for inspecting the grouting quality between the rebar and the sleeves, which are embedded prefabricated constructions. Considering the important role grouting sleeve played, we innovatively propose an ultrasonic inspection method using reverse time migration, which can distinguish the defects in prefabricated constructions. Half-grouting model is constructed to simulate the common situations in practice, while no grouting and full-grouting models are built as contrast. In constructed images, the internal information of steel sleeve can be observed with high contrast, and the location of the defects can be performed clearly. It confirms the feasibility of our proposed method.

The closed form solutions to the coil impedance change are used to study the characteristics of the circular cover meter probe coil in this paper. The solutions are confirmed by experiment, and the measured data at different frequencies can be used to correct the relative permeability of the rebar and the lift-off (the least distance from the rebar surface to the bottom of the coil). The resistance change and the magnitude of the impedance change are increasing with an increase in rebar diameter, decreasing with an increase in lift-off. But the angle of the impedance change is decreasing with an increase in lift-off slightly, decreasing with an increase in rebar diameter dramatically. These characteristics of the impedance change of circular coil can be used to design cover meter and improve its performance.

There is a need for non-destructive assay of large concrete objects like bridges and buildings. Key issues are the thickness, density and reinforcement configuration as well as indications of cracks or delamination. Furthermore, changes in the condition of concrete structures like corrosion, degradation or cavitation and voids due to ageing can pose problems. Muon scattering tomography is a non-invasive method well suited to scan large concrete samples and detect low- and high-density inclusions such as iron bars or cracks/voids in concrete. The work presented here demonstrates that with muon scattering tomography it is possible to detect rebars of a volume of 894 ± 386 cm3 in a thick concrete floor. For iron volumes above 2 500 cm3, the rebar volume can be reconstructed with a resolution of 5.4 ± 0.3% and the relative uncertainty is better than 10%. It is also shown that it is possible to image rebar structures in reinforced concrete and distinguish between single and a double layer of a rebar grid. The method was developed using Monte Carlo simulations, but it is foreseen to compare simulated data to real data collected with our muon detection system in the future.

Corrosion of carbon steel rebar in concrete structures, such as highways, bridges, and buildings have a direct impact on their structural integrity, since the rebar provides the tensile strength within the structure. Rebar strength depends on the remaining effective cross-section of a given rod. Presence of water and migration of corrosive elements, such as chloride, may result in rebar corrosion with subsequent loss of overall structural strength. In order to adequately quantify the cross-section of the ferromagnetic rod, it is necessary that the transient response is strong enough to be detected. In addition, rebar used in different applications will be placed at different depths from the outermost concrete wall. Examination of long-time decay, on five rebar samples of diameters ranging from 19 mm (0.75 in) to 57 mm (2.25 in), in the transient response of Pulsed Eddy Current (PEC) was examined as a potential method to quantify a maximum liftoff-to-size relationship. The transient response of a coaxial solenoidal drive-receive coil pair, oriented parallel to the rebar axis, was analyzed over a range of liftoffs (distance within the concrete) up to 150 mm. At times greater than ~30 ms, a single exponential decay constant appeared as a constant slope, independent of liftoff in a semi-log plot. The intercept of the linear long-time decay, in semi-log space, decreased exponentially with liftoff, and maintained a viable window for analysis up to 85 mm, 110 mm, 125 mm, 138 mm and 141 mm distances for rebar diameters of 18 mm (0.75 in), 25 mm (1 in), 38 mm (1.5 in), 51 mm (2 in) and 57 mm (2.25 in), respectively. Stated data demonstrate a power law dependence on rebar radius of limits on signal analysis due to liftoff. This report shows the potential for PEC analysis to quantify the cross-sectional area of rebar in concrete structures up to size-dependent threshold depths.

This study contributes to investigate the test of push-over flexural behavior of the newly proposed Hidden boundary one-way Rib precast concrete Slab, a so-called HRS, through a static load. Some specimens are manufactured in factory and then tested to determine design flexural strength, which are products with topping concrete and without topping concrete slabs. Those slabs are calculated for bending strength that is based on Korea domestic code, i.e., KCI 2012 (Korea Concrete Institute, 2012) with KBC 2016 (Korean Building Code, 2016). Results of the experiment verify in terms of bending strength how each structural component such as rebar, topping concrete, wire and so on of prestressed slabs with and without topping concrete components can affect static HRS flexural behaviors. In addition, the investigation at the connecting areas of precast members by using shear connector are treated. HRS slabs presented in this study, adding topping concrete, provide greater flexural strength than those without topping concrete. Finally, to obtain flexural safety, the newly developed slab may be practically utilized as one of structural members in the field of building and bridge construction. For fully applications, shear or compressive performance including structural analyses has to be tested in the near future.

An computational modelling of the reinforced concrete (RC) corrosion is developed in this work. The main purpose of this modelling is to reduce the needs of highperformance computer for the simulation of RC cylindrical column corrosion using Boundary Element Method (BEM). Thus, axisymmetric modelling was integrated to the conventional BEM in order to reduce the computational effort. In this study, the potential on whole domain of RC cylindrical column structure was modeled by Laplace equation. The corroded and non-corroded areas on the reinforcing steel (rebar) were represented by their polarization curve. The Laplace equation was solved by BEM, thus the potential on the structure can be determined. The simulation results show the similar potential distribution between conventional BEM using triangle element and developed BEM using axisymmetric element. However, BEM using axisymmetric element significantly reduce the computer effort (i.e. in term of time-consuming) for the simulation. Hence, the development of the axisymmetric modelling for BEM becomes a powerful tool to reduce the computational effort for the RC cylindrical column corrosion simulation.

When corrosion happens with the steel reinforcing bar (rebar) in concrete, the magnetic properties of the corrosion products are different from that of the steel rebar. By measuring the electromagnetic response, it is possible to judge the corrosion of steel rebar in concrete. We developed an electromagnetic method to evaluate the corrosion of steel rebar. AC magnetic field was produced by an excitation coil when AC current flow in it. Then, eddy current was induced in the surface of the steel rebar. A detection coil was used to measure the magnetic field produced by the eddy current. The signal after the amplifier was sent to a lock-in amplifier. From the lock-in amplifier, two signals were obtained: X signal (the same phase signal with the excitation current) and Y signal (90 degree phase difference signal with the excitation current). From the slope of the plotted X-Y graph using the X and Y signals, the corrosion of the steel rebar can be judged. We developed a small compact system for the corrosion evaluation of steel rebar, which will be suitable for the field experiments.

The main aim of this paper is to investigate the behavior of short concrete column reinforced longitudinally with Basalt Fiber-Reinforced Polymers (BFRP) rebar. A nonlinear 3D finite element (FE) model is developed using the commercial software ABAQUS to conduct the analysis. Geometric and material nonlinearities were utilized to simulate the inelastic large deformation of concrete material. The FE model was first validated by comparing its capability to predict the compressive strength with the analytical solution for concrete short columns reinforced with conventional steel bars. Concentric and eccentric loading cases were considered for this verification analysis. The validated FE model was then used to develop an interaction diagram for BFRP-RC short columns. Values of axial capacities and moments at different points were used to plot interaction diagrams.

The design and testing of a solution to provide energy for, and communications with, sensors encased in reinforced concrete structures, without additional wiring, was investigated. The single wire transmission line technique was adapted for use on reinforcing steel (rebar) embedded in the concrete. Experiments were conducted that first validated the approach on rebar in an ambient air medium. After the validation tests were completed, testing in concrete was conducted. To interface with the rebar special directional couplers were designed that focus the energy along the rebar in one direction. To ensure the results would be transferrable to industry, the couplers were kept physically small by using a carrier frequency of 2.4 GHz. The couplers were constructed using advanced manufacturing techniques, including laser-cut copper components and computer-aided manufacturing for the plastic dielectric members. The baseline testing in air verified that the rebar functioned as a single wire transmission line and that the coupler design worked. However, when the experimentation moved to encasement of the rebar and couplers in concrete, the performance degraded significantly. The degradation in concrete was large enough to suggest that the use of 2.4 GHz may not support either communications or energy harvesting in reinforced concrete structures. A second design approach was pursued that investigated using a much lower carrier frequency of 8 kHz. Though the degradation was not as severe as with 2.4 GHz, it was still substantial enough to indicate that the rebar single wire transmission line approach faces challenges that may warrant consideration of other techniques for embedded monitoring of reinforced concrete structures. Future areas of research were identified, including transferring the research to applications for monitoring existing steel structures in air, and also consideration of the use of this research for reinforced concrete monitoring when there are concentric steel reinforcing structures present.

One of the key factors leading to product quality improvement by reducing the imperfect product percentage on rebar production lines lies in modernization of electric motors’ control system. Known technical solutions for those systems were developed without consideration of their effect to the quality of the rebar. One of the important quality factors characteristic of the rebar is depths of notches on it. It is established that the electric motors that drive the rebar line’s units can affect the depths of notches on the processed rebar wire. The objective of this paper is the development of the unwinding machine’s electric motor control system algorithm which would decrease imperfect product percentage caused by the deviation of the depths of notches on the wire from desired values. The objective was achieved based on analytical methods for solving algebraic problems, computer modeling methods and statistical processing of the experimental data consisting of depths of notches values and the line’s electric motors’ load torque alteration values. Novelty of the paper is in proposing new control algorithm for the unwinding machine electric motor. That algorithm stabilizes rebar wire tension on a specified level at the inlet of profile stand by the means of alteration of the breaking torque that is produced by the unwinding machine’s electric motor. That, in turn, decreases depths of notches deviation. As a result of the implementation of this algorithm there was obtained decrease in rebar percentage that has depths of notches out of allowable range from 7.2 % to 1.1 %.

Detecting the corrosion of reinforcing steel in concrete is important in order to prevent early failure of reinforced concrete (RC) structures. On the other hand, the conventional methods as the half-cell potential method still have limitations to detect the corrosion. Hence, the development of a computational method to overcome the limitations is very promising. One of the methods is boundary element inverse analysis (BEIA). However, the influence of numerical parameters on the performance of BEIA still needs to be explored. The aim of this research is to study the effect of inconstant inertia weight (W) on BEIA in order to locate reinforcing steel/rebar corrosion in concrete. BEIA was developed using the boundary element method (BEM) and particle swarm optimization (PSO). In performing BEIA, several electrical potential data which measured from half-cell potential measurements were taken as a reference. Numerical simulation on simplified RC with single corrosion shows that the corrosion on rebar can be detected with reasonable accuracy, i.e., the error is less than 5% when the gradient of W along iteration up >0.5 has a significant effect on the BEIA performance in locating the corrosion.

This paper presents the design and working of a prototype rebar bending machine which is capable of manufacturing rectangular frames using continuous aluminum wire of diameter 3mm. Various mechanisms involve feeding and bending of wire and separation of product. Stepper motors being cheap, reliable and robust have been used as actuators for different mechanisms. Arduino nano microcontroller provides control signals to different stepper drivers which primarily amplify the weak control signals and their H-bridges perform reversal of current in the windings of bi-polar stepper motors. Programs uploaded in microcontroller for motion control have been written in Arduino software (IDE).

Ground penetrating radar (GPR) has been widely used for non-destructive evaluation (NDE) of concrete structures, which are usually reinforced by steel rebar. This paper investigates the penetration and scattering of electromagnetic waves through rebar nets. A numerical model simulating an infinite rebar net is established, as shown in Figure 1(a). To save the computation resource and time, only two rebar, respectively in the x and y directions, are modeled. A perfect electric conductor (PEC) condition and a perfect magnetic conductor (PMC) condition are applied to the two boundaries. Consequently, an infinite periodically-spaced rebar net is modelled, according to the mirror’s principle. In this model, two layers of rebar net with an air spacing in the z direction are included.

Rebar Bending is one of the important trade in the construction industry. Major motor skill like force of bend, bend angle accuracy, lever positioning, lever tilting are guiding factor for doing the manual rebar bending process. To be an expert in rebar bending, one should need at least 3 to 4 years of field experience, to learn all motor skill parameters. This paper describes in detail the skill parameters involved during the manual rebar bending process through experimental methods. Comparing the expert data with novice which outline the design of real time guidance system for effective skill transfer and learning. The lever positioning skill learning in manual rebar bending process projected a high accuracy with the help of feedback system.

Ground Penetrating Radar (GPR) measurement plays a key geophysical investigation to delineate rebar, thickness of concrete lining on a horse-shoe spillway, and condition of rock foundation of an earthen dam, Huai Mea Tor, Tak province, Thailand. By applying 2-D GPR, more than a hundred line at concrete floor of spillway, processing results particularly show rebar at depth 20 centimeter and thickness of concrete at 1.6 meter, as well as anomalies in several lines. Subsequence, applying Hilbert transform [5] to the 2-D data, the result displays clearer than original that easy to interpretation. In consequence, applying 3-D processing, the result reveals gridding rebar of 20×20 centimeter at depth between 20 and 40 centimeter as well as anomalous bodies at lower part of concrete floor. The anomalies can be interpreted as potential open cracks or fracture or partial property-lost concrete which may possibly be the weak zone or leakage path that water can approach to the spillway structure under pressure. Finally, treatment at spillway was performed by engineer and for a while after the leakage problem was completely stopped.

We investigated the possibility of surrounding waves along with perimeter of large diameter tendon ducts during ground penetrating radar (GPR) testing of concrete structures. The surrounding waves influence the primary reflection from tendon duct and alter the phase as well as amplitude of signal depending on the diameter of the tendon duct. This phenomenon was studied in detail by conducting several simulations using a commercial software Reflexw®. Finite Difference Time Domain method was adopted to analyze reflection patterns from objects of various diameters located at different depths in concrete media. The proposed methodology will be useful in qualitative assessment of size of metallic objects greater than a diameter of 6 cm. In general, the identification of large diameter tendon ducts in a civil structure is carried out by prior knowledge of the civil plan and its diagonal appearance to smaller diameter object mesh. The proposed methodology will enhance the confidence in identification of the larger diameter tendon ducts even if the civil plan is not known accurately.

Ground Penetrating Radar (GPR) is widely utilized as a Non-destructive technique by transportation authorities for inspection of bridge decks due to its ability to identify major subsurface defects in a short span of time. The attenuation of recorded signal at rebar level form a characteristic hyperbolic shape in profiles obtained from GPR scans and corresponds to the corrosiveness state of concrete. The detection of these hyperbolic regions is of paramount importance and is a precursor to successful interpretation of GPR data. This paper aims to automate the detection of hyperbolic regions or hyperbolas in GPR profiles based on Viola-Jones Algorithm. A custom detector is obtained through training with numerous samples of hyperbolas over multiple stages. The detection is achieved through the developed detector and it was applied over a complete bridge deck for validation purpose. The eventual goal of such detection is to facilitate the automation of GPR data analysis.

The hysteresis curve model was proposed to consider the bearing damage, the contact with the limitation device and the material nonlinearity. The calculation models of bearing, retainer were considered in the seismic response analysis. The results show that: (1) The bridge structure is unsafe under the action of large earthquakes without considering the friction effect of movable bearings. Because the friction of the movable support exists in the actual project, the structure of the first cycle of natural vibration on the weak field and considering the contribution of the movable support stiffness is closer to the field superior cycle of soil; (2) The limitation device restrains the beam displacement effectively, and reduces the seismic response of the fixed pier, and balances the distribution of seismic forces between the piers; (3) Under the conditions of large earthquake, when loss the sliding performance, the movable bearing will most likely result in the damage of piers. In the seismic design, a certain amount of rebar should be provided to ensure the ductility; (4) For different bridge structures, by changing the initial distance of the limitation device from the movable bearing, the rigidity and yield strength of the limiting device, and the coefficient and stiffness of bearing, the large displacement of the bearing could be prevent.

Corrosion of reinforcement is a major durability problem in reinforced concrete structures. This makes it prudent to assess the corrosion behaviour of rebar. Determination of corrosion current density (Icorr) values for the rebar caters to the aforesaid assessment. There are a number of methods available for determination of the same in the laboratory such as open circuit potential (OCP), surface potential measurement (SP), concrete resistivity measurements, linear polarization measurement (LPR) etc. However, most of the laboratory assessments are destructive in nature and henceforth, effective use of an artificial neural network for predicting the corrosion current density has been presented in this paper. The artificial neural network used in this study is of multi-layered perceptron type comprising of three layers i.e. input, hidden and the output layer. After simulation training of the neural network, it was further implemented in order to predict corrosion current density for rebar. This paper presents an assessment of the obtained performance curve, regression plots, predicted values and error histogram of the algorithm used to assess the corrosion current density from the experimental (laboratory) data. Accordingly, the values of the same, predicted by the aforesaid neural network match the lab obtained values very accurately, which would further aid in various endeavours such as anticipating durability, the life of concrete structures as well as in identifying a rebar type as per a specific set of conditions.

Fiber reinforced high-strength concrete is widely used, the weakening of its bearing capacity at high temperatures and mechanism of fiber reinforced are noticed by many domestic and overseas scholars. But the research is a not enough, Paper analyze improve of performance of steel fibers, glass fibers and blend fiber after high temperature. And explain the reason of spall of high-strength concrete, introducing ways to avoid this phenomenon and how to effectively restore the damage of concrete.

It has been reported that thin concrete panels reinforced with meshed aramid fiber were able to absorb and dissipate energy from impact loads. Therefore, it is likely that internally bonded aramid fibers perform well under blast loads where high strain rates involve with the material level responses similar to that from impact loads. A series of blast tests were conducted to investigate the blast performance of reinforced concrete (RC) panels with and without internal aramid fiber reinforcement. Two steel arrangements (5RB6@225 and 11RB6@90) were selected as reinforcement for the test specimens. With each rebar arrangement, two panels were cast where one with ordinary concrete and another with aramid fiber reinforced concrete. Fiber reinforcing was performed by adding aramid fibers to the fresh concrete during the concrete mixing processes. All the aramid fiber reinforced concrete (AFRC) panels were cast with one percent of fiber volume fraction. Blast tests indicate that AFRC panels outperform RC panels in overall performance.

Construction rebars (steel concrete reinforcing bars) are used to provide structural strength and reinforcement for the concrete structure. This requires the bending and cutting of the rebar to proper size before they can be used for construction. A novel haptic based barbending simulator has been devised which enables the trainees to learn and improve the construction rebar bending skill in a safe and controlled way. With its limited assessment and reporting features, the computerised virtual training simulator proves to be effective in training. Adding the features like personalized skill tracking and predictive performance modeling holds even more potential in supporting the training program. Towards this goal, a user performance modeling needs to be done which includes an initial study on performance parameters, assessment criteria and data collection before remodeling the simulator. This paper presents a study on the performance parameters for the bar bending simulator and also evaluates its effectiveness in modeling expert and novice performances. During this study we also hypothesize the parameters that can distinguish an expert and novice performances which was validated with 2 classification techniques — Support vector machine and J48 Decision tree. While revealing the classification rules J48 algorithm provides 78.94% accuracy where as SVM provides 94.737% accuracy. The study also shows that the 2 performance parameters force applied over time and bend angle accuracy are effective to distinguish expert and novice level of expertize for the construction rebar bending skill.

Bridge condition assessment is important to maintain the quality of highway roads for public transport. Bridge deterioration with time is inevitable due to aging material, environmental wear and in some cases, inadequate maintenance. Non-destructive evaluation (NDE) methods are preferred for condition assessment for bridges, concrete buildings, and other civil structures. Some examples of NDE methods are ground penetrating radar (GPR), acoustic emission, and electrical resistivity (ER). NDE methods provide the ability to inspect a structure without causing any damage to the structure in the process. In addition, NDE methods typically cost less than other methods, since they do not require inspection sites to be evacuated prior to inspection, which greatly reduces the cost of safety related issues during the inspection process. In this paper, an autonomous robotic system equipped with three different NDE sensors is presented. The system employs GPR, ER, and a camera for data collection. The system is capable of performing real-time, cost-effective bridge deck inspection, and is comprised of a mechanical robot design and machine learning and pattern recognition methods for automated steel rebar picking to provide realtime condition maps of the corrosive deck environments.

This paper is focus on the shielding effectiveness (SE) of reinforced concrete against offline electric arcs in pantograph-catenary systems. Firstly, based on the finite integration technology (FIT), the reinforced concrete shield model is established, and the SE of the reinforced concrete is calculated and analyzed. The influence factors of different concrete structures on the SE are discussed and the shielding effectiveness of a metro station is measured. Research results show: the SE of concrete against electromagnetic wave is periodic, and the increase of thickness has little effect on the SE in the high frequency band. The SE of the rebar is greater than 30 dB in the frequency range 0.1GHz ∼ 0.8GHz. The SE of double layer reinforced concrete in the 0.1GHz∼1.3GHz is larger than 40 dB. The measured SE is in good agreement with the numerical results, which verifies the correctness of the proposed model to calculate the SE of the electric arcs in pantograph-catenary systems.

Improvement of electric drive's control systems on rebar production lines is one of the key factors that lead to the rebar quality increasing and imperfect product percentage reducing. Known technical implementations for the drives were made without consideration of the effect of their parameters to the rebar quality, particularly to the depths of notches on it. The objectives of this work are to analyze how the lines' electric drives affect the depths of notches, and based on the analysis the development of the electric drives control systems which should decrease imperfect product percentage caused by the depths of notches deviation from desired values. Solutions to the objectives were based on analytical methods for solving algebraic problems, computer modeling methods and statistical processing of the data concerning depths of notches, and the line's electric drives' load torques variations. Novelty of the paper is in proposing new technological requirements to the unwinding machine electric drive, development of a calculation method for the wire tension effect to the rebar depths of notches, unwinding machine electric drive's breaking torque alteration method with the view of wire tension stabilization on a specified level at the inlet of profile stand. As a result of industrial tests of the developed unwinding machine electric drive control system on an active production line there was obtained decrease in rebar percentage that has depths of notches out of allowable range from 7.2 % to 1.1 %.

In this paper, the influence of the coefficient of reinforcement and grade of concrete strength, crack resistance and deflection of reinforced concrete bending elements. The analysis is performed on the basis of numerical experiments three series of beams with different design resistances of rebar and interest reinforcement of stretched zones.

This paper presents the possibility of using optical measuring system ARAMIS for reinforced concrete beams behaviour studies. Measurements of spatial deformations (horizontal displacements and rotation of the cross section) and cracking process (width and number of cracks) of these elements were taken into account. Such measurements are very difficult to do with the use of traditional methods. System specification has been prepared in order to, test a large area of reinforced concrete beams. It was possible among other things, to use of two sensors/two sets of cameras. Due to this fact and the unusual use for testing of reinforced concrete elements, it was necessary to develop a procedure for reinforced concrete elements measuring. To evaluate the accuracy of measurement, uncertainty of the measurement system was calculated for the configuration used in the studies. The analysis of crack formation and corresponding displacements was based on results of tests performed on 14 single-span reinforced concrete beams monotonically loaded until failure. During studies all data were collected using optical measuring system based on ARAMIS software. On the basis of research and analysis it was demonstrated that the asymmetrical distribution of rebar in reinforced concrete beam section affects on horizontal displacements and the process of crack formation on the surface of the beam.