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Low back disorder continues to be prevalent amongst construction workers, especially the rebar workers who are often engaged in repetitive stooping postures. Wearable robots, exoskeletons, are recent ergonomic interventions currently explored in the construction industry that have potentials of reducing the risks of low back pain by augmenting users’ body parts and reducing demands on the back. This paper presents the assessment of a commercially available passive wearable robot, BackX, designed for reducing low back disorder amongst rebar workers. The study evaluated the exoskeleton in terms of task performance and physiological conditions. Outcome measures such as completion time were employed to evaluate the effect of the exoskeleton on task performance, while activations of Erector Spinae and Latissimus Dorsi muscles, and perceived discomfort across body parts were employed to assess the physiological effects of the exoskeleton. The results indicated mixed effects of the exoskeleton on muscle activations. Although the results revealed that the exoskeleton can reduce muscle activations across the Latissimus Dorsi, mixed effects were observed for the Erector Spinae especially during the forward bending tasks. The exoskeleton reduced completion time by 50% during the rebar tasks. There was also a 100% reduction in perceived discomfort on the back, but discomfort was tripled at the chest region when the exoskeleton was worn. This study reveals the potentials of the exoskeleton for reducing low back disorder and improving productivity amongst the rebar workers. However, the unintended consequences such as increased discomfort at the chest region and activations of the muscles highlight the need for improving existing exoskeleton designs for construction work.

Steel rebars for reinforced concrete usually stated in a form of bar bending schedule. In a project, an inefficient activity of cutting steel rebar can result a waste in the form of trim loss. This can lead to profit loss and cause an impact to environment. The optimization needs to be done in order to minimize the trim loss from the steel rebar cutting. Previously, there has been many studies on steel bar trim loss optimization using metaheuristic methods as well as studies on cutting pattern generator. However, if the steel rebar variation is too many, the cutting pattern generator will produce a large number of cutting patterns. Therefore, this study aims to solve the optimization problem by producing more efficient cutting pattern while still obtaining minimum trim loss at any conditions. The data used in this research is obtained from a real-life office project. In the process, the study will be comparing the performance of both PSO and SOS from each cutting patterns generator and conditions. The performance of the two methods is assessed from its minimum, maximum, average, standard deviation and the convergence graph of each iteration. The result shows that SOS performed better in finding the minimum trim loss on undersupply condition.

Diaphragm wall was adopted for the subsurface excavation for LG06 underground station, one of the Wanda line stations in Taipei MRT, and it encountered many geological challenges during construction. The geological conditions in this zone are mostly clay and hard rock layer. The unconfined compression strengths of the extremely hard rock samples were tested during construction. The results were far beyond that obtained during site investigation, and hence is a big challenge for constructing the diaphragm wall. Furthermore, the Tai-power 161 kV high-voltage power cable box is longitudinally crossing the entire station zone. It leads to great difficulty during the construction of diaphragm walls. The neighbored houses are very close to the job site and cause a high risk of diaphragm wall construction. Engineers must find the solution to protect the Tai-power cable box and the adjacent houses to prevent any disasters. This paper presents how the borehole drilling method was adopted to conquer the complicated rock problem for diaphragm wall excavation. Engineers proposed a unique method by moving the rebar cage horizontally to avoid damaging the 161 kV power concrete box. Besides, a series of grouting piles with reinforcing bars were installed before excavating guide ditches for the diaphragm wall. With the innovative mitigations, the challenges, as mentioned earlier, have been mitigated. Sustainable construction technologies were successfully executed for the diaphragm wall of the LG06 station project, Wanda line of Taipei MRT.

The reinforcing bar (rebar) produced by Tempcore process had tempered martensite structure on its surface, owing to quenching and tempering, and ferrite–pearlite structure at the core owing to slow cooling rate. Bainite, a low-temperature transformation phase, was observed in the transition area. Mechanical properties of the rebar are significantly influenced by area ratio and hardness of the tempered martensite. In this study, microstructure and area ratio of the tempered martensite of the rebar produced by the Tempcore process were predicted using finite volume method and a continuous cooling transformation diagram. The area ratio of the tempered martensite was predicted with error range of ± 6%. Furthermore, association between the microstructure and hardness was determined by a non-isothermal tempering experiment. The hardness of the tempered martensite was successfully predicted using the tempering temperature with R-squared 98%. The proposed methodology can be effectively used to control the mechanical properties of the rebars.

Super ductile thermo-mechanically treated (SD TMT) reinforcing steel bars are commonly used these days for RC constructions given their excellent thermal and seismic resistant properties. The superior performance of SD TMT rebars is due to their distinct cross-sectional phase distribution (CSPD) of martensite, bainite, and pearlite, which impart better combinations of strength and ductility than conventional classes of steel. This paper presents an investigation carried out to study the influence of corrosion-induced damage to cross-sectional phase distribution (CSPD) on mechanical properties of SD TMT bars in comparison with the performance of conventional mild steel and ordinary TMT steel bars exposed to an aggressive environment. The influence of corrosion-induced damage to cross-sectional phase distribution (CSPD) on the stress–strain response of SD TMT bars has been investigated through tensile tests in a displacement controlled UTM. The study involved tensile tests carried out on SD TMT bars corroded to 25 different levels ranging from (0–45%) on five different rebar diameters (8mmO, 10mmO, 12mmO, 16mmO and 20mmO). The results suggest better characteristic performance of SD TMT steel bars over conventional hot-rolled rebars in mechanical behaviour's critical aspects. A correlation predicting the reduction of mechanical properties of corroded TMT bars' residual capacity concerning corrosion percentage has been suggested.

Substitution of only steel rebar with fiber-reinforced polymer (FRP) or in combination with steel rebar has been recommended to reduce corrosion effects in steel rebar. This paper has pursued the impact of hybrid concrete beams reinforced with High Strength Steel Bars (HSS) and Glass Fiber-Reinforced Polymer Bars (GFRP) manufactured employing High-Performance Fiber-Reinforced Cementitious Composites (HPFRCC) instead of conventional concrete through experimental tests. Seven concrete beams including conventional concrete and HPFRCC in three separate groups, having identical compressive strengths and longitudinal steel reinforcement ratios, have been tested following respected codes and regulations to supply sufficient development lengths using GFRP headed bars, under four-point loading tests. The first and second groups, each represented one conventional concrete beam and an HPFRCC model with GRFP or HSS; the third group included three HPFRCC beams using GRFP and Steel rebar to assess flexural behavior of beams under different reinforcement ratios. Experimental results indicated that HPFRCC beams demonstrated improvements in their load capacity, flexural strength, bending stiffness, ductility, and energy absorption compared to similar conventional concrete beams. Also, in hybrid beams compared to steel reinforced concrete beams both cast with HPFRCC, the more the effective reinforcement ratio of both single and hybrid bars increased, the more ductility was improved between 37 and 88 percent. Displacement ductility of hybrid beams having effective reinforcement ratios up to 1.35 and 1.25 times more than the balance ratio was increased 23 and 37.5 percent, respectively. Energy absorption for HPFRCC beams reinforced only with GFRP or steel rebar was increased 31 and 250 percent compared to identical conventional concrete beams, respectively. In hybrid compared to GFRP reinforced beams both cast with HPFRCC, the more effective reinforcement ratio increased, the more energy absorption was increased in a range of 51 up to 174 percent. Therefore, it can be concluded that using the hybrid of GFRP and HSS bars result in up to 30 percent improvement in flexural strength because of the effective performance of GFRP after steel rebar yielding and ductility increase due to HSSs yielding.

The external wall insulation and fire prevention problems are hard to solve due to the lack of economical insulating and flame-retardant materials. By taking the wallboard structure as the cut-in point, a novel ceramsite concrete composite wallboard is proposed in this study, which inputs the insulation materials inbetween two wallboards to not only solve the fire prevention problem of the insulation materials thoroughly, but also prevent peeling-off of insulation wall during the construction and using processes. In order to apply this type of wallboard in shear wall structure, a T-shaped joint component of the new ceramsite concrete composite wallboard that adopts U-shaped rebar connection way is proposed in this paper as well. Three same specimens and one contrast specimen are designed in total. Meanwhile the seismic performance of the joint is also studied through the low-cyclic reversed loading experiment. And both the experimental phenomenon and the failure mechanism show that, shearing failure is the failure form of the specimen. The core area of the joint plays a dominating role during the stress process. By analyzing the seismic parameters of the specimen, such as hysteresis, skeleton, ductility and energy consumption, conclusions are made that the specimen is featured in good overall seismic performance, meeting the design requirement of “strong joint, weak component” in the specifications. The study on the T-shaped joint of the novel ceramsite concrete wallboard complements the connection methods of this new type of insulation wallboard, and provides a reliable basis for applying this type of wallboard in practical construction.

Relevance. In recent years, composite materials have become widespread in the construction of reinforced concrete structures for industrial, civil and transport structures. It is proposed to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite rebar. It took an experimental and theoretical substantiation of technical solutions to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite reinforcement. The aim of the work was to carry out a set of experimental and theoretical studies of the stress-strain state and internal forces in low-reinforced concrete structures of hydraulic structures reinforced with prestressed basalt composite rebar. Methods. Experimental studies of the stress-strain state and internal forces were carried out on the basis of low-reinforced concrete beam-type models with interblock construction joints, harden with prestressed basalt composite reinforcement in the stretched (compressed) zones of the models. Theoretical studies of the stress-strain state and internal forces were carried out on the basis of the theory of reinforced concrete and structural mechanics. Results. As a result of the research carried out on typical low-reinforced concrete structures of hydraulic structures with interblock construction joints, the main stages of the stress-strain state of hydraulic reinforced concrete structures were formulated. Based on the data of experimental and theoretical studies, taking into account the reinforcement with prestressed basalt composite rebar, as well as with prestressed clamps in the shear zone, a method was developed for calculating the strength of low-reinforced hydrotechnical reinforced concrete structures with interblock construction joints.

To reduce the amount of reinforcement and control crack width, ultra-high strength rebar reinforced Engineered Cementitious Composites (UHSRRE) beams are considered a promising choice. A model is developed for predicting the flexure deflection of UHSRRE beams in service stage based on internal force equilibrium and the compatibility of deformation. In this model, the bilinear stress–strain model for Engineered Cementitious Composites (ECC) and ultra-high strength rebar is adopted, and the tensile zone of UHSRRE beams is considered. The flexure tests of seven beams with different reinforcing ratios and matrix materials are carried out for verifying the proposed model. It is observed that the experimental results are basically consistent with the predicted results. This model can provide a useful tool for the calculation of deflection. Additionally, parametric analysis is conducted to analyze the influence of reinforcement bars and matrix materials on the bending deformation of UHSRRE beams. Through comparison of the results, it is found that using higher strength grade bars not only reduces the amount of reinforcement but also maintains excellent bending performance.

Concrete with the addition of polypropylene fibres is more cohesive and has better adhesion, deformability and tightness because the fibres “bind” the concrete matrix together and prevent large pores from forming in the concrete mix and limit the formation and spread of shrinkage cracks. Therefore, it can be assumed that polypropylene fibres affect the effectiveness of the concrete cover as a layer protecting steel bars against corrosion. This article presents the results of tests allowing us to estimate the effect of addition of polypropylene fibres on the reduction of reinforcing bars corrosion in concrete caused by the action of chlorides. Evaluation of the degree of corrosion of the reinforcement was analysed using the electrochemical polarisation galvanostatic pulse technique. The use of such a method allowed for the quantitative estimation of the effect of the addition of polypropylene fibre on the reduction of corrosion activity of the reinforcement in concrete.

Polymer coatings can be used to mitigate the corrosion of steel in high-chloride environments. Obtaining speciation information from thin corrosion layers can be important for understanding corrosion mechanisms, including polymer coating failure. This study outlines the effectiveness of collecting glancing angle x-ray absorption near edge spectroscopy (GA-XANES) spectra at the Fe K-edge to obtain chemical speciation information at the polymer/steel interface without removal of the polymer film. The depth of penetration of the incident x rays can be altered by changing the incidence angle, allowing for more fluorescence signal from corrosion products to be detected relative to the Fe metal fluorescence signal in GA-XANES spectra. This study demonstrates the use of GA-XANES to study thin layers of steel corrosion and obtain depth profile information of steel corrosion products beneath a polymethyl methacrylate polymer coating.

Based on magnetic medium theory, a newly invited magnetic corrosion detector (MCD) showed great potential in quantitative monitoring the corrosion process of steel rebar in concrete. To furtherly explore the application performance of MCD, a numerical model was established to simulate the magnetic induction intensity variation caused by corrosion of steel rebar. And the influence of the length and the positioning variance of steel rebar on the measurement were discussed based on experimental and numerical investigation. The research results indicate that the numerical simulation is a valid approach to reveal the essential performance of MCD in measuring the corrosion ratio of steel rebar in concrete. Based on the geometric and physical properties of MCD, the corrosion ratio of the steel rebar can be effectively measured. And the positioning variance of steel rebar has significant influence on the precision and sensitivity of MCD. It is suggested that the steel rebar should be placed right at the center of the test area during the measurement to achieve a high accuracy.

This article presents the materials of deformability studies of pre-stressed steel-concrete beams reinforced with a package of reinforcement with different ratio of tape and rebar in the pure bending moment zone. The aim of the research was determination of the reinforcement percentage influence, for pre-stressed reinforced concrete beams reinforced with a package of reinforcement on their deformability. Also, the aim was to evaluate the effectiveness of using pre-stressed rebar in combined reinforcement. The practical significance of the experimental research is to study the deformability in pre-stressed bending elements with external tape and rebar reinforcement, taking into account the influence of different ratios of reinforcement areas within the combined reinforcement and development of proposals for such structures` calculation and design. The scientific novelty of the research is in obtaining the deformability characteristics of reinforced concrete beams reinforced with a package of reinforcement (tape and steel bars with periodic profile) with different ratios in the case of static loads` action.

The present study has been focused on the environment-friendly corrosion inhibitor. Conifer cone (Pinus resinosa) has been used as a novel corrosion inhibitor to mitigate the corrosion of steel rebars in simulated concrete pore solutions (SCPS) in the presence and absence of chloride ions. The corrosion inhibitor is extracted by simple chemical methods. The functional groups present in the extracted conifer cone (ECC) powder are characterized as well as the surface morphology of ECC has been examined. The corrosion inhibition performance has been evaluated by the electrochemical and weight loss methods. The experimental results indicate that ECC possesses a corrosion inhibition efficiency of 81.2% at a dosage of 1000 mg·L-1, after 720 h of immersion in chloride-contaminated SCPS. Adsorption isotherm and their standard Gibbs free energy (ΔGads0) values are calculated by Langmuir, Freundlich, and Temkin isotherm methods, and the results indicate that the ECC is initially adsorbed on the steel rebar surface by physisorption and then it turns to chemisorption. The steel rebar surfaces have been characterized after exposure to the ECC containing SCPS, and the results indicate that the ECC containing cationic adsorbate molecules, which interact with steel rebar, leads to retardation of metal dissolution in corrosive chloride medium.

Roadways in thick coal seams are widely distributed in China. However, due to the relatively developed cracks and brittleness of coal, the support failure of thick-coal-seam roadways frequently occurs. Therefore, the study of bolt failure characteristics and new anchoring technology is very important for the safety control of thick-coal-seam roadways. Based on field observations, the failure mechanism of selected roadway failures under distinct conditions at three representative coal mines in eastern and western China was analyzed. Recommendations are provided for roadway safety control. The results show that the strength and dimension of the anchoring structure in the coal roof of thick-coal-seam roadways are the decisive factors for the resistance of the roadway convergence and stress disturbance. The thick anchoring structure in the roof constructed by flexible long bolts can effectively solve the problem of support failure caused by insufficient support length of traditional rebar bolts under the condition of extra-thick coal roof and thick coal roof with weak interlayers. The concepts and techniques presented in the paper provide a reference for the design of roadway support under similar geological conditions and dynamic load.

A simplified reinforcement model is proposed to consider the effects of both corrosion and reinforcement slip-on seismic performance of reinforced concrete columns. The mechanical properties deterioration of corroded reinforcement are obtained by regression analysis of the available experimental data. Since corrosion may also have a significant influence on bond-slip, a local bond-slip curve with corrosion effect is constructed, by shifting the curve for uncorroded rebar in the slip direction. To fully consider the non-uniformity of bond stress distribution along the development length, a stepped equivalent bond stress is used to simplify the integral calculation of theoretical slip. Subsequently, the cumulative slip and the equivalent strain with slip effect are formulated to modify the parameters of monotonic and hysteretic models of perfectly bonded corroded reinforcement. The response of corroded reinforced concrete columns under cyclic loading is simulated by the fiber section beam element model. Finally, the numerical simulation results and the experimental data are compared. The results show that the ignorance of slip will overestimate the stiffness and bearing capacity of the column by 28.3 and 13.5% respectively, and the yield load, peak load and peak lateral displacement of column decrease with corrosion in longitudinal reinforcement gradually, by 33.8, 16.3 and 56.6% for mass loss percentage 8.0%, respectively. This confirms the ability of the proposed model to simulate the nonlinear seismic response of structures in a corrosive environment.

In a comprehensive investigation, the simultaneous effectiveness of the factors of temperature (five temperatures), volume ratio of steel fibers (three volume ratios), and concrete cover thickness over the rebar (three covers) on the compressive strength, tensile strength, and concrete-steel rebar bond behavior was evaluated. 180 specimens comprised of 45 cubic specimens for the compression test, 45 cylindrical specimens for the splitting tensile strength test, and 90 prismatic specimens for the pull-out test were made. The results demonstrated raising the temperature reduced the compressive strength such that the strength of the plain specimens after exposure to 800 ℃ declined by 71.6%, compared to that of the corresponding non-heated specimens. Moreover, at a given temperature, the presence of steel fibers improved the tensile strength. After exposure to 800 ℃, the tensile strength of specimens with 1% steel fibers in volume was 127.9% higher than that of similar specimens without fibers. At a given temperature, the use and content of steel fibers had an effective role in compensating for losses in the tensile strength and bond strength induced by applying heat. Furthermore, as the concrete cover over the rebar increased, the failure mode became more ductile. The effect of steel fibers on increasing the bond strength of the specimens with a thinner concrete cover heated at elevated temperature was greater and more noticeable. Also, the concrete cover over the rebar had an effective role in compensating for the heat-induced bond strength loss, such that increasing the concrete cover from 25 to 65 mm easily compensated for the concrete-rebar bond strength reduction for every 200 ℃ increment in the exposure temperature.

Spliced region is a place where the concrete-rebar bond plays a significant role, and reduced bond strength in this region negatively affects the structure safety and integrity due to corrosion. This research has studied the combined corrosion effects of the main reinforcements and stirrups in the spliced region on the concrete-rebar bond strength in lap-spliced beams. A total of 15 lap-spliced RC beams with different stirrup spacing in the spliced region failed under 4-point bending; tensile bar and stirrup corrosions were the variables in this study. Finally, Response Surface Methodology (RSM) was used for estimating the relative bond strength of this beams. According to the results, adding corroded stirrups in the spliced region will cause negative effects on the bond strength in beam specimens via combined tensile bar-stirrup corrosion in the spliced region. Gradients in the descending part of the curve for relative bond strength versus corrosion were calculated at −0.0154, −0.016 and −0.017 when stirrups are 1, 2 and 3, respectively. Also, beams with 25% corrosion have the largest increase in the stirrup-induced bond strength. The results show that the model presented by RSM is in good agreement with the experimental results.

The effect of additives on the performance, durability and multi-functional service sustainability of a novel self-compacting concrete (SCC) was investigated in this research. Constant partial replacement of cement with 40% fly ash and admixture of M25 grade conplast SP 430 were used to form the SCC. This was followed with the addition of varying amount (0–4%) of diethanolamine as an organic corrosion inhibitor, while one set of concrete was made without the additive, to act as a control. The effect of the additives on the compressive strength, split tensile strength, the corrosion rate of the reinforcement steel rebar and the ability of electrical energy being harnessed from the concrete were analyzed. It was observed that the amount of diethanolamine to be added for maximum enhancement of mechanical properties and corrosion resistance of SCC was 3.2%. The mechanical properties of the SCC and its corrosion resistance were found to be better. Also, the energy that could power some DC components and devices was harvested or generated from the concrete beam. Hence, the study concluded that diethanolamine is a good corrosion inhibitor for reinforced concrete steel rebar and that the presence of fly ash and admixture of M25 grade conplast SP 430, strengthened the concrete.

Objective: To design, fabricate and evaluate the new features of a portable manual rebar bender, a Hand Tool that is used for bending rebar and other malleable materials. Methods: The researcher improves on the previously available portable manual rebar bender. Experts assessed the acceptability of this bender in terms of design and portability. Furthermore, as previously stated, the study significantly improves the usefulness of the inexpensively produced bending machine for reinforcing concrete with negligible human force. Findings: The device created has a valuable impact on the construction industry’s human force due to its affordability and marketability. Also,the present tools guaranteed strength, durability, and lightness in weight. Furthermore, the portable manual rebar is made of different elements such as a center axle, stationary backup roller, and sleeve. The results after ten trials showed that the portable manual rebar bender could finish 9 mm, 20mm, and 12 mm stirrup at an average of 24.3 seconds, 26.3 seconds, and 27.7 seconds, respectively. Additional results from seven to ten trials showed the bending time for 24 seconds stirrup for 9mm, 26 seconds stirrups for 10 mm, and 28 seconds stirrup for 12 mm. Furthermore, after a series of ten trials, the instrument achieved an accurate angle bent of 90 degrees. The M= 4.77 and 4.82 are very acceptable in terms of design and portability tools based on the evaluators’ rating. Novelty: The design is novel in terms of cost, portability, and efficiency. The device can be a great help in the structures and buildings. Furthermore, the construction industry will use the portable manual rebar bender to build houses and other local infrastructure to test its effectiveness. Then, the researcher is encouraged to engage in another research to try the innovation. Keywords: Improvised; Innovative; Locally made; Device; Bender

Reinforcement corrosion is a major culprit that undermines the service life of reinforced concrete (RC) structures. It costs billions of dollars each year in the US alone and negatively impacts safety, reliability, resilience, and environmental performance of RC infrastructure. Corrosion monitoring of steel rebar is critical to provide early warning of deficiency, enable timely and effective maintenance strategies, and prevent catastrophes associated with premature failure of RC structures. To improve corrosion monitoring in the engineering practice, this work comprehensively reviews the state of the art of five major types of techniques, that is, electrochemical sensors, optical fiber sensors, sensors based on elastic wave methods, sensing based on electromagnetic methods, and untouched sensors. Each type of technique is systematically divided into sub-categories based on the sensing principle and key characteristics. For each sensor type, its maturity, application range, and the problems that hinder its application are discussed, aimed to provide guidance in selecting the appropriate sensors for specific engineering applications. This work concludes with an overview of opportunities and challenges, including the following six aspects for future research: spatial resolution, sensitivity, and measurement range; reliability and interpretation of the measurement; sensor selection based on three corrosion stages of steel rebar; long-term stability and service life; cost-efficiency of the sensing system; and monitoring of existing structure.

The paper shows the results of an experimental campaign aimed at investigating the cyclic behavior of a column-to-foundation joint for precast concrete elements. The tested connection is realized adopting corrugated steel ducts embedded into the foundation, in which column protruding rebars are anchored by grouting high performance mortar. The experimental program consists in testing six full-scale reinforced concrete square-section columns subject to quasi-static cyclic lateral load with a constant axial compression. A preliminary series of bond tests was carried out to define some experimental variables, i.e., longitudinal rebar diameter and anchorage length. Results of the precast joints are compared with those of two reference cast-in-place specimens with the same geometric characteristics, showing similar hysteretic behavior, energy dissipation and ductility values. Lastly, the plastic hinge height is computed for all the specimens based on experimental concrete strains, and compared to current codes formulations.

This article presents the results of experimental studies of reinforcement with prestressed basalt-composite rebar in the tensile zone of the structure. The studies were performed on beam type models, taking into account the characteristic aspects of the reinforced concrete structures of the hydraulic engineering construction (HEC). Reinforcement is made by the method of tension “on concrete.” The models were tested for bending moment and transverse force.

Combining fiber reinforced polymer (FRP) with seawater sea-sand concrete (SSC) can solve the shortage of river sand that will be used for marine engineering construction. The bond performance of BFRP bars and SSC specimens is researched by pull-out test in this paper. The effects of the parameters, such as bar type, bar diameter, concrete type and stirrup restraint, are considered. It is beneficial to the bonding performance by the reduction of bar diameter. The utilization of seawater sea-sand has a low influence on the bond properties of concrete. The bond strength of BFRP is slightly lower than the steel rebar, but the difference is relatively small. The failure mode of the specimen can be changed and the interfacial bond stress can be improved by stirrups restraint. The bond-slip curves of BFRP ribbed rebar include micro slip stage, slip stage, descent stage and residual stage. The bond stress shows the cycle attenuation pattern of sine in the residual stage. In addition, the bond-slip model of BFRP and SSC is obtained according to the experimental results and related literature, while the predicted curve is also consistent well with the measured curve.

A model is developed for moisture absorption by rebar made of basalt fiber-reinforced polymer composite (BFRP), taking account of Fick diffusion, structural relaxation, and the design features of the rebar in the initial stages of climatic aging. The model is experimentally confirmed. The analytical solution may be used for kinematic approximation of moisture absorption by other reinforced polymer composites.

The formation of open porosity in rebar made of basalt fiber-reinforced polymer composite (BFRP) is investigated during exposure tests in northern climates. A statistical model is proposed for pore formation in BFRP rebar.

Ground-penetrating radar (GPR) has been widely applied to the nondestructive inspection of concrete structures such as tunnel lining, bridge deck, and retaining wall, which are usually reinforced by steel bars. The scattering of electromagnetic (EM) waves caused by the dense steel rebar embedded in the concrete structures has a severe influence on the penetration capacity of GPR waves. In this letter, the scattering and penetration characteristics of EM waves propagating through rebar net are investigated via both numerical and laboratory experiments, with an aim to select the antenna nominal frequency for a different reinforcement density. The results show that the rebar, which is perpendicular to the polarization direction of GPR waves and has a very small diameter compared with the wavelength, is almost transparent to the impinged GPR waves. The scattering and interaction of GPR waves caused by the rebar that is parallel to the polarization direction result in a shielding effect, which is manifested as a blind band in the low-frequency range in the transmitted spectrum. This result violates the rule of thumb commonly used in the GPR community, i.e., the lower frequency has a deeper GPR penetration depth. In the end, a low cutoff frequency is recommended for selecting a GPR antenna with an appropriate nominal frequency when it is used in the detection of an anomaly inside and behind a reinforced concrete structure, in which the spacing of the rebar net is known.

A technique to enhance the mechanical and thermal properties of flat radomes integrated with high-power horns is presented. Specifically, metallic strips, referred to as rebars (from reinforcing bars), are deployed as structural reinforcement across the radome-enclosed antenna aperture. This enables the use of thinner, more fragile materials, with lower loss and permittivity, as protective covers without detrimentally affecting the RF performance. A maximum gain greater than 15.4 dBi and voltage standing wave ratio (VSWR) < 1.5 are maintained with the rebar across the 18–45 GHz band for a given horn and radome. Moreover, the pressurization handling for the baseline radome is improved from 5 to 14 psig while theoretically maintaining the ability to support 750 W of continuous wave power. The studies are carried out in the electrical, thermal, and mechanical domains.

Recently the application of self-compacting concrete (SCC) has emerging in construction structures due to its good abilities to improve durability and decrease bleeding with good bonding with rebar. On the other hand, large amount of aggregates is required for the production of SCC. However; replacing natural aggregate in SCC with waste materials can led to discover ecological building materials. Walnut shell (WS) is one of the agriculture waste materials which can be used as a substitution of aggregate in SCC. In this research, WS was used as a replacement of coarse aggregate for constructing SCC by employing ten different volume fractions from 5% to 50% with each increment of 5%. Fresh and hardened properties of SCC were investigated for all mixes and control one. The results showed that all tested properties decreased by increase WS volume fraction. However; the lightweight self- compacting concrete (LWSCC) can get at fraction volume of WS equal and or more than 35%. Where, slump flow diameter (SFD), compressive and bond strengths were 560 mm, 35 MPa and 6.55 MPa respectively achieved at 35% ratio of WS.

The shape memory alloys (SMAs) are special materials able to withstand large non-elastic deformations regaining their original form by removing stress. High fatigue strength and proper resistance to corrosive agents are the specific characteristics of these alloys. This article explores the SMA and carbon fiber reinforced polymer (CFRP) at designated points of reinforced concrete (RC) structures to evaluate the behavior against selected earthquakes. Three RC frames with 5, 10 and 15 stories were modeled and various cases were considered for SMA location in different story levels and for each structure, there are 8 different cases. In the first part, the incremental dynamic analysis (IDA) was employed to assess the entire range of structural dynamic behavior using 13 ground-motion far-field records set. In the second part, by using the produced data from IDA method, fragility evaluation was conducted on multiple limit states to provide a comprehensive performance assessment for each case. The extracted graphs show that the strengthening of the frames studied by the SMA rebar and the CFRP layers, causes an increase in the maximum drift rates and spectral acceleration (Sa) and thus increases the ductility. Consequently, the rate of probability of seismic damage decreased and the frame is more resistant to collapse.

A substantial amount of work was carried out on the use of fiber-reinforced polymer (FRP) in reinforced concrete structural elements, which demonstrated considerable inelasticity or deformity through monotonic and cyclic loads. Even so, the action of FRP bars in reinforced concrete columns and frame structures has not yet been studied during reversed cyclic loading. In this research, reversed cyclic loading was applied on three beam-column joint models using the finite element method with ANSYS software. The first model was for a joint designed with steel rebar for both the longitudinal and transversal reinforcement. Glass fiber reinforced polymer (GFRP) rebar was used in the second joint model for the longitudinal reinforcement with steel transversal reinforcement. The third joint model was designed with hybrid steel/GFRP reinforcement for the longitudinal reinforcement and steel transversal reinforcement. The performance of the three models under reversed cyclic loading, such as load vs. story drift and energy dissipation capacity, were compared. The GFRP-reinforced model displayed a predominantly elastic behavior up to failure. Although its energy dissipation was lower, its performance in terms of total story drift demand was satisfactory

The present work deals with the investigation of core compressive strength in reinforced concrete column with the slip angle orientation and bond stress relationship using Magneto rheological fluid...

As part of ongoing research to validate the efficacy of a potentiodynamic polarization technique of determining the critical chloride threshold (CCRIT) value of steel reinforcing bars exposed to ch...