Journal of Science and Transport Technology

Influence of Graphene Oxide (GO) and Fly Ash (FA) on the workability and mechanical properties of self-compacting concrete

Wed, 14 May 2025 00:00:00 +0000

Self-compacting concrete (SCC) is an advanced material for complex construction applications requiring accurate formwork, high reinforcement density, and superior surface finishes. The ability to flow and consolidate under its weight eliminates the need for mechanical vibration, thereby improving construction efficiency, reducing labor costs, and ensuring greater homogeneity. SCC is widely employed in underground structures, high-rise buildings, and load-bearing elements where strength, durability, and workability are critical. Graphene oxide (GO) and fly ash (FA) enhance SCC's performance. GO enhances compressive strength, crack resistance, and durability through microstructural refinement and crack propagation inhibition, while FA improves workability, reduces water demand, and increases durability by lowering permeability and shrinkage. The partnership between GO and FA meets SCC performance standards and enhances its applicability in high-performance and sustainable construction. This study examined the effects of GO content (0% and 0.03% by binder weight) and FA content (15%, 25%, and 35%) on the workability and mechanical qualities of SCC. A series of studies were performed to assess the workability features of SCC, together with two principal mechanical properties: compressive strength and flexural tensile strength at 28 days. The findings demonstrate that while an increase in GO content diminishes flowability owing to its elevated specific surface area, the appropriate incorporation of FA mitigates this effect, leading to a combination with enhanced mechanical properties. SCC with 0.03% GO and 25% FA attained the maximum compressive strength at 28 days.

An application of the response surface method to structural optimization problems

Anh Tuan Tran, Nhu Son Doan — Wed, 14 May 2025 00:00:00 +0000

Structural problems are commonly analyzed using implicit solvers, such as the finite element method (FEM), which often demand manual processes and are computationally intensive, especially for structural optimization problems that involve multiple FEM evaluations to identify the optimal design solutions. In addition, implementing optimization algorithms also demands significant expertise for accurate application. This study proposes a simple yet efficient procedure to address structural optimization problems by transforming the implicit analysis into explicit performance functions using the response surface method and simulating the space of input variables by random samples. The explicit performance functions enable quick evaluations for all generated samples of inputs, and a search routine is developed to identify optimal solutions efficiently. The proposed procedure is validated through three case studies, demonstrating its ability to achieve accurate solutions within minutes of analysis.

Enhancing Seismic Performance of Reinforced Concrete Exterior Joints with Ultra-high-performance Steel Fiber Reinforced Concrete: A Parametric Finite Element Study

Trung-Hieu Tran — Wed, 14 May 2025 00:00:00 +0000

Beam-column joints are vital to the stability and performance of reinforced concrete (RC) frame structures, particularly under seismic conditions. Understanding their stress-strain behavior is crucial for evaluating their capacity and ductility. However, performing detailed experimental studies with numerous specimens is often impractical due to significant costs and time constraints. As a result, finite element (FE) analysis, supported by tools like ABAQUS, has become a preferred approach for studying joint behavior effectively. This study employs the finite element method (FEM) to analyze exterior beam-column joints designed for high ductility (DCH) and enhanced with ultra-high-performance steel fiber reinforced concrete (UHPSFRC). The FE results are validated against experimental data through comparisons of load-displacement responses, failure patterns, and reinforcement strain progression. Furthermore, the research examines the effects of parameters like UHPSFRC strengthening length, axial column load, and steel fiber content on joint tensile stress, providing insights into optimizing seismic performance.