Journal of Science and Technology in Civil Engineering (JSTCE) - HUCE

2024-03-25T10:14:10+00:00

Experimental study on the effectiveness of strengthening of reinforced concrete beams with opening in shear span using CFRP sheets

2024-03-25T10:11:35+00:00

In reinforced concrete beams, the opening is frequently required for the passage of utility ducts and/or pipes. The presence of such web openings leads to a reduction of the strength and stiffness of the beam. To ensure
the safety of the reinforced concrete beam, a strengthening system around the opening is necessary. This paper
aims to contribute to a better understanding of the shear behavior of reinforced concrete beams with openings
in the shear span, strengthened with Carbon fiber-reinforced polymer (CFRP) sheets. The study is based on an
experimental program carried out on six beams. All beam specimens were 850 mm long with a cross-section
of 150 × 250 mm and a shear span to beam depth ratio (a/d) of 1.48. One beam without any openings served as
the control specimen, while the remaining five beams featured circular or rectangular openings within the shear
span and with/without shear strengthening using CFRP sheets around the openings. The test results obtained
from this experimental program provide insights into the shear behavior of beams with openings, both with and
without strengthening using CFRP sheets. Additionally, the potential advantages and effectiveness of employing
CFRP strengthening techniques for opening strengthening are investigated and discussed.

Effect of fiber content on flexural fracture parameters of high-performance steel fiber-reinforced concrete

2024-03-25T10:11:35+00:00

This study deals with the effect of fiber content on fracture parameters of high-performance steel-fiber-reinforced concretes through a bending test program. All the high-performance steel-fiber-reinforced concretes flexural specimens were tested under configuration of three-point loading. The fracture parameters were hardening energy, softening energy and length of cohesive crack. Two steel fiber types were employed in the studied high-performance steel-fiber-reinforced concretes, including 35 mm long hooked fiber and 13 mm short smooth fiber. The high-performance steel-fiber-reinforced concretes were produced from the same matrix but added different fiber contents as follows: 0.0 vol.%, 0.5 vol.%, 1.0 vol.%, and 1.5 vol.%. The experimental results
demonstrated that two parameters, including the hardening energy and softening energy, were observed to increase with increasing of fiber content, regardless of fiber type. The hardening energy was lower than the
softening energy at any fiber content. The short smooth fibers generally produced the higher fracture energy
parameters than the long hooked fibers. The highest total fracture energies of the high-performance steel-fiber-reinforced concretes were observed at 1.0 vol.% as follows: 58.25 kJ/m²for using short smooth and 59.16 kJ/m²for using long hooked fibers. Besides, the addition of reinforcing fibers considerably improved the length of the cohesive crack of the high-performance steel-fiber-reinforced concretes: from 0.58 mm using no fiber to 519.85 mm using short smooth fibers 0.5 vol.%.

Numerical investigation of shear behavior of steel fiber reinforced concrete beams without stirrups subjected to an asymmetric point load

2024-03-27T08:03:29+00:00

Steel fibers have been shown in numerous studies to enhance the shear performance of steel fiber reinforced concrete (SFRC) beams effectively, and to evaluate the shear behavior of these beams, a nonlinear finite element (NLFE) analysis is required. In the present study, from recent experimental results of asymmetrical loading tests on SFRC beams without stirrups, three NLFE models have been validated and further developed to evaluate the impact that the ratio of shear span-to-depth (a/d) and the compressive strength of steel fiber concrete (SFC) have on the shear behavior and shear strength of SFRC beams without stirrups. The validation shows a good agreement between the chosen NLFE model and the reported experimental results. Applying the NLFE model to five different values of the a/d ratio (e.g., 1.0, 1.5, 2.0, 2.54, and 3.1) reveals a gradual decline in shear strength, while the ductility of the beam increases with the increase in ratio. Meanwhile, with increasing SFC compressive strength, the shear strength and ductility of SFRC beams without stirrups significantly increase for the same ratio of shear span-to-depth. Moreover, the failure mode of SFRC beams without stirrups dominantly depends on the a/d ratio.

Static and dynamic behaviour of sandwich beams with porous core: Experiment and moving least squares mesh-free analysis

2024-03-25T10:11:36+00:00

In this paper, the static and dynamic behaviour of sandwich beams with porous core are numerically analyzed
and validated by experimental tests. The beam consists of a thick porous core with a uniform porosity distribution over its domain and two outer face layers. For the theoretical study, the virtual work principle is employed to derive the governing equation. A one-dimensional (1D) mesh-free approach, associated with the moving least squares Hermite interpolation, is developed to approximate the primary variable fields and discretize the governing equation. Additionally, a simple transformation method is applied to create Kronecker delta property of constructed shape functions, straightforwardly facilitating the imposition of the boundary condition, similar to the finite element method without additional techniques. The accuracy of the computational method is subsequently verified against previous literature. For the experimental tests, various mechanical responses, such as the natural frequency, static deflection, and deflection-time history of a cantilever porous sandwich beam consisting of cemboard faces and a concrete core with Expanded Polystyrene are measured and compared with the theoretical prediction. The outcomes of this study can be valuable for the design of sandwich beams with porous core.

Influence of recycled steel fiber on the properties of self-compacting concrete with high fly ash content

2024-03-25T14:34:40+00:00

The recycled steel fibers from waste steel cables have properties suitable for enhancing the load-bearing capacity, impact resistance, and shrinkage reduction of Self-Compacting Concrete (SCC). The use of a high content of fly ash in SCC reduces production costs and is environment friendly by minimizing the amount of cement in the mix. This article presents the experimental research results on the influence of the content of recycled steel fibers on the properties of high-fly-ash SCC. The research utilized recycled steel fibers from elevator steel cables with volume percentages of 0%, 0.5%, 1% and 1.5% respectively in SCC, with a fly ash content in the SCC mix of 50% by volume of powder. The evaluated properties included workability, plastic shrinkage, drying shrinkage compressive strength, and tensile strength. The results indicate that using recycled steel fibers with a maximum content of 1% enables the production of SCC that meets European standards for workability. In addition, when comparing SCC with 0.5% and 1% recycled steel fiber content to control SCC samples (without steel fibers), the compressive strength of SCC increased by 5.04% and 7.56% respectively, the tensile strength increased by 2.99% and 5.97% respectively, plastic shrinkage decreased by 27.34% and 30.47% respectively, and 28-day drying shrinkage decreased by 3.2% and 4.6% respectively. Using recycled steel fibers combined with high-volume fly ash is a reasonable solution to save production costs and be environmentally friendly. Additionally, this solution not only improves the compressive and tensile strength but also limits plastic and drying shrinkage deformations of SCC. As a result, the durability of SCC is enhanced.

Understanding the correlates of construction safety of high-rise buildings: A Bayesian perspective

2024-03-25T10:11:36+00:00

Safety in high-rise building construction is a critical concern, particularly in the densely populated urban areas of Vietnam. Understanding the complex interplay of factors influencing safety on construction sites is essential for reducing accidents and enhancing overall project outcomes. This study aims to identify and analyze key factors impacting safety in high-rise construction projects. Utilizing Bayesian Poisson Regression, the research investigates the relationship between various safety-related factors and the occurrence of non-fatal accidents. The study adopts a comprehensive approach, selecting potential safety factors from the existing literature and developing a rating system validated by site safety managers. Data were collected from 48 high-rise building
projects in Vietnam, constructed between 2019 and 2022. Bayesian Poisson Regression was employed to analyze the impact of 15 variables on safety outcomes, including management commitment, worker participation,
training programs, emergency preparedness, and safety inspections. The findings underscore the multifaceted
nature of construction safety and the need for a holistic approach that involves strong safety training, engaged
management and workers, protective measures, and proactive safety audits. This research provides actionable
insights for practitioners and contributes to the academic discourse on construction safety, emphasizing the
utility of Bayesian methods in unraveling complex safety dynamics in high-rise construction.

Modeling of organizational behavior framwork for road usage charge management

2024-03-25T10:11:36+00:00

Organizational behavior plays a crucial role in effective management. However, there is limited research on
organizational behaviors in road usage charging management. This study aims to address this gap by identifying six dimensions of organizational behavior through focus group studies. Questionnaires were administered to 138 professionals in Vietnam, and the data were analyzed using structural equation modeling. The findings revealed six behavioral dimensions: Responsibilities fulfillment (OR1), Progress assurance (OR2), Aligned implementation organization (OR3), Hierarchical and delegated management (OR4), Efficient operation system (OR5), and Transparency and accountability assurance (OR6). Among these dimensions, OR2, OR4, and OR6 significantly impact management performance. Additionally, OR2 mediates the relationship between OR1 and management performance, OR4 mediates between OR3 and OR5, and OR5 indirectly influences management performance through OR6. It is expected that the efficacy of this approach will strengthen the significance of the organizing function and offer a valuable instrument to aid professionals in the field of road usage management.

Assessment of waste management scenarios toward marine plastic debris mitigation and cost reduction

2024-03-25T10:11:36+00:00

The increase in solid waste volume and change in composition due to urban development cause negative effects on the marine ecological environment. The aim of this study was to assess the amount of plastic waste leaking into the environment from the municipal solid waste (MSW) management system and propose mitigation measures towards sustainable development in Hue city, Viet Nam. The method of modelling MSW management system applying Material Flow Analysis (MFA) and simulating models through scenarios were used to propose strategic solutions to improve and develop the system. As a result, the implementation of segregation at source and improvement of the current collection system are urgently needed. Integrated treatment system including material recovery facility combined with transfer station, incineration, centralized and decentralized composting treatment can reduce the landfilled amount to 5% and the quantity of mismanaged plastic waste infiltrating the ocean has undergone a substantial reduction of several hundred-fold.

Critical review of capacitive deionization: design, operation consideration and real-world environmental applications

2024-03-25T10:11:36+00:00

Capacitive Deionization (CDI) has emerged as a promising and environmentally sound solution for addressing pressing water treatment challenges. This critical review meticulously examines the design, operational considerations, and performance metrics of CDI systems, particularly highlighting their significance in environmental applications under real-world conditions for handling different water sources such as groundwater, surface water, sea water. Various CDI configurations, electrode materials, and operational parameters are scrutinized through an extensive analysis of literature, with their direct influence on system efficiency, ion removal capacities, and long-term stability being elucidated. The reduced energy consumption, minimal chemical usage, and potential for sustainable water treatment of CDI, as compared to traditional methods, are emphasized from an environmental perspective. Moreover, this review underscores the pivotal role of CDI in practical environmental applications, including desalination, wastewater treatment, and remediation of inorganic pollutants (heavy metals and hardness) and resource recovery (nutrient, uranium, lithium…). By presenting compelling case studies, CDI's efficacy in mitigating environmental impacts is illustrated, offering a cleaner and more cost-effective alternative to conventional treatment methods. By outlining challenges and charting future directions, this review serves as a roadmap for researchers, engineers, and policymakers, facilitating the development of sustainable and efficient water treatment strategies. In an era marked by escalating environmental concerns, CDI emerges as a potential technology for responsible and effective water management, poised to shape a more sustainable future.

Utilizing numerical simulation to determine the reasonable parameters for the design of hydraulic rock-splitting head

2024-03-25T10:11:36+00:00

The hydraulic rock splitter with a wedge-type splitting head has various advantages, such as simple operation, high work efficiency, safety, shortened work time, and minimal environmental impact. The splitting head driven by a hydraulic cylinder, is the focus of this research, as it directly influences work efficiency. This paper introduces the general structure of the rock splitter machine and the hydraulic cylinder-driven splitting head, along with the method for selecting suitable parameters. To evaluate and select suitable variables, this study establishes procedures and calculation methods for two sets of problems: determining the parameters for the wedge and the parameters for the hydraulic cylinder. The numerical test results provide a design dataset applicable to real-world scenarios, including the wedge angle, cylinder stroke, cylinder diameter, pressure, minimum cylinder wall thickness, and piston rod diameter, corresponding to the respective rock-splitting forces. These parameters meet the set objectives of cylinder pushing force and minimize the cross-sectional area of the cylinder body, contributing to weight reduction and operational convenience.

Energy evolution of gravitational-granular flows

2024-03-25T10:11:36+00:00

The catastrophe of natural disasters such as landslides, is a prevalent phenomenon in natural terrain conditions in high mountainous areas; however, the mobility of such landslides has not yet well understood due to the discrete nature of material and the coming to play of water. In this paper, we numerically study the mobility of an unsaturated gravitational-granular flow, occurring on a slope-break system that contains two regions: inclined-upstream and horizontal-downstream areas, by using three-dimensional discrete element simulations. A sliding volume composed of spherical grains collapses on the first region, then plunges and deposits on the second one. The upstream-plunging length and the cohesive stress exerted on grains affect differently on the energy evolution not only in the whole process but also in different regions and directions depending on the inclination angle. These findings provide a deep understanding of the mechanism and mobility of landslides, leading to good predictions about the potential impacts of the catastrophic landslides on buildings and human lives.

A comparative study of two correlation functions applying to the quantitative characterization of the pore structure within hardened concrete

2024-03-25T10:11:36+00:00

The paper presents a comparative study between the autocorrelation function (ACF) and the 2-point correlation function (2PCF) for the quantitative analysis of the pore structure within hardened concrete via the image analysis technique. This work was carried out on five cross-sectional images of concrete specimens with varying area porosities ranging from 2.6% to 21.2%. This research indicates that: (i) the ACF provides a comprehensive and effective tool that is capable of capturing the contribution of the area porosity, size, and orientation of the pores in quantifying the pore structure within hardened concrete, while the 2PCF only enables quantifying the size and spacing between the pores; (ii) the ACF requires the cross-sectional images to be square, whereas the 2PCF can analyze images of any size and shape; (iii) for an area porosity below 20%, the characteristic size of the pore structure within hardened concrete, determined by both the ACF and 2PCF approaches, is not significantly different; (iv) on average, the correlation length estimated by 2PCF is more than 1.6 times greater than the corresponding value determined by ACF; and (v) the characteristic size provides a more accurate and comprehensive quantification of the pore structure within hardened concrete specimens than the correlation length.

Journal of Science and Technology in Civil Engineering (JSTCE) - HUCE

Table of Contents

Experimental study on the effectiveness of strengthening of reinforced concrete beams with opening in shear span using CFRP sheets

Effect of fiber content on flexural fracture parameters of high-performance steel fiber-reinforced concrete

Numerical investigation of shear behavior of steel fiber reinforced concrete beams without stirrups subjected to an asymmetric point load

Static and dynamic behaviour of sandwich beams with porous core: Experiment and moving least squares mesh-free analysis

Influence of recycled steel fiber on the properties of self-compacting concrete with high fly ash content

Understanding the correlates of construction safety of high-rise buildings: A Bayesian perspective

Modeling of organizational behavior framwork for road usage charge management

Assessment of waste management scenarios toward marine plastic debris mitigation and cost reduction

Critical review of capacitive deionization: design, operation consideration and real-world environmental applications

Utilizing numerical simulation to determine the reasonable parameters for the design of hydraulic rock-splitting head

Energy evolution of gravitational-granular flows

A comparative study of two correlation functions applying to the quantitative characterization of the pore structure within hardened concrete