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This paper aims to investigate the necessary requirements that a concrete reinforcement material must satisfy; namely the ability to resist tensile forces and have good bond strength while providing structural qualities of toughness and flexural strength.

The bond and strength properties were mainly tested in a paired comparison test using 6 mm diameter steel and fibre reinforced polymer (FRP) rebar specimens in beams and cubes. Bond strength was examined using 12 concrete cube specimens of 150 mm, six cubes had steel rebar and six had FRP rebar inserted through the full depth of the cube and they were subject to pull out tests. To determine flexural strength and toughness, a three point loading test was performed to provide load/extension data on 28 500×100×100 mm concrete beams. A total of 14 beams were cast with steel rebar and 14 were cast with FRP rebar.

The results showed for equal diameter bars the FRP specimens had outperformed steel in each test. Failure modes of FRP specimens showed higher degrees of toughness when compared to steel.

Steel rebar has a long and proven track record of satisfactory use in reinforced concrete. For designers and clients to change from traditionally used materials, there is a need for investigative research to prove the worth of the new material. This paper goes part of the way to fulfil this need.

The purpose of this paper is to present the results of a two-year long study carried out in order to evaluate the corrosion performance of mild steel bare bars (BB) and epoxy-coated rebar (ECR) in concrete under a simulated harsh environment of chlorides.

The blocks are subjected to Southern Exposure testing. The electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and Tafel plot are performed to measure the polarization resistance and corrosion current densities of these rebars. Knife-peel test was performed to assess the adhesion between epoxy and underlying steel after two years of exposure.

Mild steel BB showed a high corrosion current density of 1.24 µA/ cm² in Tafel plots and a very low polarization resistance of 4.5 kΩ cm² in LPR technique, whereas very high charge transfer resistance of 1672 and 1675 kΩ cm² is observed on ECR and ECR with controlled damage (ECRCD), through EIS technique, respectively. EIS is observed to be a suitable tool to detect the defects in epoxy coatings. After two years of immersion in 3.89 percent NaCl⁻ solution, the mild steel BB were severely corroded and a considerable weight loss was observed, whereas under heavy chloride attack, ECR showed no deterioration of epoxy coating and neither any corrosion of underlying steel. Results of this study show that the durability of reinforced concrete (RC) structures with respect to corrosion could be enhanced by using ECR, especially in harsh climatic conditions.

The corrosion performance of mild steel and ECR in concrete under a simulating splash zone environment is evaluated. EIS was used to evaluate the health of epoxy and corrosion state of underneath steel rebars. EIS was able to detect the defects in epoxy. The durability of RC structures could be enhanced in harsh climate regions by using ECR.

The combination of an Engineered Cementitious Composite (ECC) layer and steel plate to reinforce RC beams (ESRB) is a new strengthening method. The ESRB was proposed based on the steel plate at the bottom of RC beams, aiming to solve the problem of over-reinforced RC beams and improve the bearing capacity of RC beams without affecting their ductility.

In this paper, the finite element model of ESRB was established by ABAQUS. The results were compared with the experimental results of ESRB in previous studies and the reliability of the finite element model was verified. On this basis, parameters such as the width of the steel plate, thickness of the ECC layer, damage degree of the original beam and cross-sectional area of longitudinal tensile rebar were analyzed by the verified finite element model. Based on the load–deflection curve of ESRB, ESRB was discussed in terms of ultimate bearing capacity and ductility.

The results demonstrate that when the width of the steel plate increases, the ultimate load of ESRB increases to 133.22 kN by 11.58% as well as the ductility index increases to 2.39. With the increase of the damage degree of the original beam, the ultimate load of ESRB decreases by 23.7%–91.09 kN and the ductility index decreases to 1.90. With the enhancement of the cross-sectional area of longitudinal tensile rebar, the ultimate bearing capacity of ESRB increases to 126.75 kN by 6.2% and the ductility index elevates to 2.30. Finally, a calculation model for predicting the flexural capacity of ESRB is proposed. The calculated results of the model are in line with the experimental results.

Based on the comparative analysis of the test results and numerical simulation results of 11 test beams, this investigation verified the accuracy and reliability of the finite element simulation from the aspects of load–deflection curve, characteristic load and failure mode. Furthermore, based on load–deflection curve, the effects of steel plate width, ECC layer thickness, damage degree of the original beam and cross-sectional area of longitudinal tensile rebar on the ultimate bearing capacity and ductility of ESRB were discussed. Finally, a simplified method was put forward to further verify the effectiveness of ESRB through analytical calculation.

Failure of a critical reinforced concrete beam due to fatigue can have severe safety and production consequences, and preventative repair/replacement of such a beam is expensive. It would therefore be beneficial if repair/replacement can be done based on an accurately and conservatively predicted remaining useful life (RUL). The purpose of this paper is to develop such a model.

Condition-based maintenance is a maintenance approach that uses empirical/analytical models and a measurable condition to predict remaining useful life. The P-F curve (condition-life) is a useful tool that can aid in making these decisions. A model to create a P-F curve is developed using rebar fatigue test results (in the form of an S–N curve) and the Palmgren-Miner law of damage accumulation. A Monte Carlo simulation with statistical distributions is employed to provide confidence levels of RUL outputs.

An example of how the model can successfully be used in practice is shown in this paper, and a sensitivity study is performed leading to conclusions being drawn with regard to damage tolerant design considerations.

If a critical reinforced concrete beam fails due to fatigue can have serious consequences. This paper develops a model to help base repair/replacement decisions based on accurately and conservatively predicted RUL. Financial and safety benefits would be gained if this model would be used in practice.

This paper aims to identify an inhibitor to protect rebar corrosion in concrete.

The authors use the simple method of polarization and calculate the change in open-circuit potential and corrosion current density.

Sodium molybdate is an efficient inhibitor compared with sodium tungstate for rebar corrosion in concrete.

This paper has limitation of 0.0001 M concentration of inhibitors for 400 days of exposure in 3.5 per cent sodium chloride solution.

The research focused on the concentration of both inhibitors in the range from 0.1 to 0.0001 M, which resulted in greater structural protection from corrosion in adverse conditions, such as coastal areas.

The purpose of the investigation was to research the corrosion resistance of water‐cooled rebar quenched in a novel agent (CQ) named CQ‐cooled rebar.

Water‐cooled rebar was quenched in CQ about 1 s, then cooled in air. The corrosion resistance of water‐cooled rebar and CQ‐cooled rebar was evaluated by atmospheric exposure (AE) and wet/dry cyclic accelerated corrosion tests (CCT). The electrochemical properties of the two rebar scales were researched using electrochemical tests, and their compositions and structure were examined using XRD, SEM and FT‐IR.

The corrosion tests showed that the corrosion resistance of CQ‐cooled rebar was better than that of water‐cooled rebar. The electrochemical tests indicated that the CQ‐cooled rebar scale had a higher corrosion potential, a lower corrosion current density and a higher polarization resistance. The thickness of the scale was 56 μm for CQ‐cooled rebar, and 29 μm for water‐cooled rebar. The phase constitution of the two scales comprised Fe₂O₃, Fe₃O₄, 2FeO · SiO₂ and FeO, but the mass ratio of Fe₂O₃ and Fe₃O₄ to 2FeO · SiO₂ and FeO, called protective ability index of the scale (PAIS), changed from 0.45 for water‐cooled rebar to 24 for CQ‐cooled rebar.

The results clarified the role of CQ‐quenching in improving the corrosion resistance of water‐cooled rebar, which was to generate thick and compact Fe₃O₄ and Fe₂O₃ layers over the rebar substrate, and retard the anodic dissolution and cathodic hydrogen evolution reaction.

Strategic Management.

The case is designed for a) MBA students b) Short-duration executive MBA courses.

The case refers to India’s leading steel company Tata Steel. Tata Tiscon, the steel rebar brand, is the organization’s leading retail brand. The case chronicles the period between the birth of the retail brand in the year 2000, its dramatic rise and dominance, to the end of 2013 when some of its initiatives had failed. Tata Tiscon was established as a pan Indian brand on the dint of a distribution network comprising 33 distributors and over 2000 retailers, many of them exclusive to the brand. The brand spawned a series of innovation in the category like “selling by piece”, fixed price concept and “free” home delivery. Together with its channel partners, the company achieved dramatic success which was reflected in its leading market share coupled with significant price premium in a category where price had traditionally being the only selling pitch. After 2010, the company saw an emerging challenge in the form of a new business model, where some companies were gearing to provide the complete portfolio of construction material including cement, steel, etc., and a turnkey construction solution for house builders. Tata Tiscon responded by attempting to enter the service space by launching a building design solution and later a construction supervision solution. Both of these initiatives failed. The protagonist of the case is Mr Keshav Viswanath (Chief of Marketing for retail business at Tata Steel), who is concerned with the failures of these key initiatives and is wondering how to ensure the “leader” status of Tata Tiscon in coming years.

The students are expected to understand how a core strategy like differentiation is implemented successfully in “practice”; understand the exploitation–exploration dichotomy in an organization; appreciate difference between radical innovation (based on new organizational routines, new business partners and new relationships) and incremental innovation based on fine tuning of existing organizational routines and relationships.

Rebar production: www.youtube.com/watch?v=J6n9sci8j-8; Tata TISCON AV: www.youtube.com/watch?v=89kOUsbnaYQ; TQM – The Toyota Way: www.youstube.com/watch?v=qf3gdrIMxRw; Disruptive vs. Incremental Innovation: www.youtube.com/watch?v=kOOL_GiaLTo; Approach to innovation is dead wrong: www.youtube.com/watch?v=pii8tTx1UYM

CSS 11: Strategy.

This study investigates the impact of the fire decay phase on structural damage using the sectional analysis method. The primary objective of this work is to forecast the non-dimensional capacity parameters for the axial and flexural load-carrying capacity of reinforced concrete (RC) sections for heating and the subsequent post-heating phase (decay phase) of the fire.

The sectional analysis method is used to determine the moment and axial capacities. The findings of sectional analysis and heat transfer for the heating stage are initially validated, and the analysis subsequently proceeds to determine the load capacity during the fire’s heating and decay phases by appropriately incorporating non-dimensional sectional and material parameters. The numerical analysis includes four fire curves with different cooling rates and steel percentages.

The study’s findings indicate that the rate at which the cooling process occurs after undergoing heating substantially impacts the axial and flexural capacity. The maximum degradation in axial and flexural capacity occurred in the range of 15–20% for cooling rates of 3 °C/min and 5 °C/min as compared to the capacity obtained at 120 min of heating for all steel percentages. As the fire cooling rate reduced to 1 °C/min, the highest deterioration in axial and flexural capacity reached 48–50% and 42–46%, respectively, in the post-heating stage.

The established non-dimensional parameters for axial and flexural capacity are limited to the analysed section in the study owing to the thermal profile, however, this can be modified depending on the section geometry and fire scenario.

The study primarily focusses on the degradation of axial and flexural capacity at various time intervals during the entire fire exposure, including heating and cooling. The findings obtained showed that following the completion of the fire’s heating phase, the structural capacity continued to decrease over the subsequent post-heating period. It is recommended that structural members' fire resistance designs encompass both the heating and cooling phases of a fire. Since the capacity degradation varies with fire duration, the conventional method is inadequate to design the load capacity for appropriate fire safety. Therefore, it is essential to adopt a performance-based approach while designing structural elements' capacity for the desired fire resistance rating. The proposed technique of using non-dimensional parameters will effectively support predicting the load capacity for required fire resistance.

The fire-resistant requirements for reinforced concrete structures are generally established based on standard fire exposure conditions, which account for the fire growth phase. However, it is important to note that concrete structures can experience internal damage over time during the decay phase of fires, which can be quantitatively determined using the proposed non-dimensional parameter approach.

This study aims to investigate the size effect of the patched repairing material applied to the cracked beam.

Numerical analysis was conducted on a simply supported cracked beam with a dimension of 200 × 25 × 15 cm using ABAQUS software. The behavior of concrete and engineered cementitious composites (ECC) in the simulation are described as concrete damage plasticity model. Linear elastic-plastic model was used to represent the behavior of rebar steel. The type of patching consisted of the varying ratio of lengths and depths, including patching length to total length ratios of 0.2, 0.3 and 0.4, and patching depth to total depth ratios of 0.2, 0.3, 0.4 and 0.5.

Results show that variations in the patching length and depth ratios affect the maximum flexural load, stiffness and ductility of the repaired beam. It was also found that repairing the cracked beam by using ECC provides higher flexural load of the beam than the use of conventional concrete, owing to the superior tensile strength of ECC.

ECC is the cementitious-based mortar that contains the special selected poly vinyl alcohol fiber having high tensile strength. ECC has been known to exhibit high ductility, high tensile strength and improve durability performance. Thus, ECC is suitable as repairing material for patching cracked beam. By investigating the size of the patched repairing material applied to the cracked beam, the structural performance of repairing beam and the effectiveness of the various patching size were achieved.