Efficient load transmission between concrete and steel reinforcement by bonding action is a key factor in the process of the design procedure of bar-reinforced concrete structures. To enhance the bond strength of steel/concrete composites, the impact of graphene nanoplatelets (GnP) on the bond stress and bond stress–slip response of deformed reinforcement bars, embedded in high-performance concrete (HPC), was investigated using bar pullout tests. In the current study, 36 samples were produced and examined. The main variables were the percentages of GnP, the steel reinforcement bar diameter, and embedded length. Bond behavior, failure mode, and bond stress-slip response were studied. Based on the experimental findings, the inclusion of GnP had a significant favorable influence on the bar-matrix interactions due to the bridging action of GnP as a nano reinforcement. For 0.02 wt.% of GnP, the bond strength was enhanced by more than 41.28% and 53.90% for steel bar diameters of 10 and 16 mm, respectively. The HPC-GnP mixture displayed a reduction in the initial slippage in comparison to the control sample. The test findings were compared to the prediction models created by other researchers and the ACI 408R-12 code.

In current practice, the performance-based concrete mix (PBCM) approach has become quite popular because it enhances the quality of materials that are fundamentally necessary for a particular situation. In the present study, experimental analysis is performed to determine the optimal mechanical properties and microstructural characteristics of concrete for sustainable development and cost effectiveness. Specifically, a mixture of high-volume fly ash (FA) and ultrafine calcium carbonate (UFCC) is investigated as a partial substitution of cement. For optimizing the concrete’s performance, various curing regimes are applied to evaluate the best conditions for obtaining ideal mechanical and microstructural properties. The results show that concrete containing 10% UFCC with a mean particle size of 3.5 µm blended with 40% FA yielded the best performance, with an enhancement of 25% in the compressive strength in the early age. Moreover, the UFCC improved the compactness and refined the interstitial transition zone (ITZ). However, the effects of the different curing methods on the concrete’s strength were insignificant after 28 days.

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The effects of the surface waves generated by the wind have a significant effect on the currents. A wave current coupled model plays an important role in the design offshore structures. The interaction between fluids such as incompressible ocean waves and current and offshore structures is significant with many real-time applications in offshore engineering. These coupled models can be applied to Offshore Floating Production Operating and offloading (FPSO), Wind or current turbines and offshore pipelines. The complex issues related to the design are analyzed by using Computational Fluid Dynamics, which requires an investigation of the multiphase flow between wave and current and the structure which is considered restrictive due to the computational cost. If viscous effects are neglected then the single-phase flow models have been recommended, where wave-current interaction have been modelled successfully. Models have been developed where velocities and pressure are computed and the results can be verified with the experimental results available in the literature. In this study the existing numerical methods, mesh types are discussed along with their coupling methods. Here single-phase and multiphase models with small and medium movement are reviewed and their applications are highlighted. Commercial CFD code ANSYS Fluent has been found most reliable and easy to use tool for the analysis of fluid flow interacting with offshore structures near the free surface. It can successfully be used for determination of fluid dynamics of offshore environments installed complex multi-component structures. Dynamic mesh facility is more useful for multiphase modelling of floating structures.

Offshore structures play a vital role in the economy of offshore oil-producing countries, where mostly fixed jacket type structures are used to produce oil and gas installed in shallow water. In an offshore environment where structures are installed, there exist met ocean forces such as wind, waves, and currents. These met ocean conditions when interacting with offshore structures near the free surface, generate loads. The estimation of such loads is very much important for the proper design of these structures. The primary aim of this study is to investigate the interaction of waves with a jacket platform by generating offshore environments in the numerical wave tank (NWT). To achieve this goal, ANSYS Fluent is used for the flow analysis by using continuity and Navier Stokes equation. Results are verified and validated with the analytical work. Wave crests under operating condition generate a force of 1.3 MN which is the lowest in magnitude as compared to wave crest which produces 4.5 MN force under extreme conditions. Unlike operating wave crest, the operating wave trough generates a higher force of 1 MN than extreme conditions which account for 1.5 MN forces. Forces produced by the extreme offshore environment are 30% higher than those generated under operating conditions. It is concluded from the results that a positive force is exerted onto the structure during the water entry phase while a negative force is observed when the water leaves the structure.