Journal of Materials and Engineering Structures
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Sustainable Development of High-Volume Fly Ash Self-Compacting Concrete Incorporating Bottom Ash and Recycled Concrete Aggregates
Full text linkIncorporating by-products like coal bottom ash (BA), recycled concrete aggregates (RCA), and fly ash (FYA) in concrete is an essential step toward green and sustainable development in construction sector. For sustainable utilization of RCA as natural coarse aggregates (NCA) and BA as natural fine aggregates (NFA) in high-volume fly ash self-compacting concrete (HVFYA-SCC), this study investigates ten numbers of designed HVFYA-SCC mixes. HVFYA-SCC mixes were developed with varying content of ordinary Portland cement, FYA (60%), NCA, NFA, RCA (maximum 50%) and BA (maximum 30%). The substitution of 20% BA and 25% RCA in HVFYA-SCC mixes increased compressive and split tensile strengths after 120 days of curing, while further substitution (s) led to a drop in properties. Similarly, at 120 days of curing the maximum electrical resistivity was achieved (20% BA and 25% RCA), while all mixes under ultrasonic pulse velocity resulted in the ‘good category.’ Also, the same mix resulted in lower sorptivity values for maximum curing. A good correlation (R2 0.8) was observed among the tested mechanical and durability properties. The outcomes of this study indicate valuable information on the performance and potential benefits of using HVFYA-SCC in advanced structural designs for upcoming concrete industry. Furthermore, the findings successfully support the implementation of designed concretes as sustainable and environmentally-friendly alternative to conventional concrete(s)
Seismic Behaviour of a Single Span Historical Masonry Bridge
Full text linkA major portion of the cultural heritage consists of old structures that are susceptible to earthquakes. These structures are prone to significant damage from natural disasters, particularly earthquakes. This study's primary goal is to assess the historical masonry bridge's seismic response to strong far-fault ground motions (FFGM) and near-fault ground motions (NFGM). The historical Sultan Suyu Masonry Bridge is used as a case study in this study. It was created with three-dimensional finite element software. The time history response of the bridge model is contrasted with one another in terms of stresses and displacements produced for FFGM and NFGM. The assessments take into account the FFGM and NFGM of the 1999 Düzce, 1999 Kocaeli, and 1992 Erzincan earthquakes, which had nearly equal peak ground accelerations. The results show that FFGM is equally significant as NFGM and that FFGM could be used in conjunction with NFGM to further evaluation of historical masonry arch bridges
Advanced Composite Materials and Structures
Full text linkComposite materials are used to produce multi-objective structures such as fluid reservoirs, transmission pipes, heat exchangers, pressure vessels due to high strength and stiffness to density ratios and improved corrosion resistance. The mathematical concepts can be used to simulate and analyze the generated mechanical and thermal properties of composite materials regarding to the desired performances in actual working conditions. To solve and obtain the exact solution of the developed nonlinear differential equations in the composite materials, analytical methods can be applied. Mechanical and thermal analysis of complex composite structures can be numerically analyzed using the Finite Element Method (FEM) to increase performances of composite structures in different working conditions. To decrease failure rate and increase performances of composite structures under complex loading system, thermal stress and effects of static and dynamic loads on the designed shapes of composite structures can be analytically investigated. The stresses and deformation of the composite materials under the complex applied loads can be calculated by using the FEM method in order to be used in terms of safety enhancement of composite structures. To increase the safety level as well as performances of the composite structures in different working conditions, crack development in elastic composites can be simulated and analyzed. To develop and optimize the process of composite deigning in terms of mechanical as well as thermal properties under different mechanical and thermal loading conditions, the advanced machine learning systems can be applied. A review in recent development of composite materials and structures is presented in the study and future research works are also suggested. Thus, to increase performances of composite materials and structures under complex loading systems, advanced methodology of composite designing and modification procedures can be provided by reviewing and assessing recent achievements in the published papers
Comparative relevant aspects regarding lightweight concrete containing polystyrene beads
Full text linkGenerally, the main of this experimental work is to found new resources in materials of constructions, especially with the interdiction of the exploitation of some sea sand careers. Thus, advanced constructors use light products, which is going to represent a primordial advantage in the reduction of the seismic risks, because the seismic strength represents a fraction of the total mass of the construction.Moreover, the use of lightweight materials and concrete gives a prime advantage in Algeria regarding the earthquake so try to lighten the slabs as much as possible. Lightweight aggregate concrete is characterized by a combination of cement and low-hardness aggregate. These aggregates have the characteristics of high porosity; they can absorb a large proportion of water from fresh concrete, which reflects the water demand of lightweight aggregate. The latter is also seriously affected by the surface structure and shape of the aggregates used. Based on fly ash aggregate and polystyrene concrete, this paper studies the preparation of lightweight concrete with different amounts of polystyrene concrete instead of fly ash sand. The results show that the cement quality and aggregate density affect the workability and lightweight of concrete
Damage detection for a large-scale truss bridge using Tranmissibility and ANNAOA
Full text linkIn this paper, we propose an efficient approach to enhance the capacity of Artificial Neural Network (ANN) to deal with Structural Health Monitoring (SHM) problems. Over the last decades, ANN has been extensively utilized for damage detection in structures. In order to identify damages, ANN frequently utilizes input information that is based on dynamic features such as mode shapes or natural frequencies. However, this type of data may not be able to detect minor damages if the structural defects are insignificant. To transcend these limitations, in this work, we propose utilizing transmissibility to create input data for the input layer of ANN. Moreover, to deal with local minimum problems of ANN, a combination between the Arithmetic Optimization Algorithm (AOA) and ANN is proposed. The global search capacity of AOA is employed to remedy the local minima of ANN. To evaluate the effectiveness of the proposed approach, a numerical model with different damage scenarios is considered. The suggested approach detects damage location precisely and with higher severity detection precision than the conventional ANN method
Study on the performance of natural fiber reinforced concrete of different strength with DIP technique and T- Test Analysis
Full text linkThis work focuses on the effect of natural plant fiber as reinforcement on the strength properties of concrete of different grade strength (M30-M50). Fibers of different length were added to the concrete mix at the rate 3% of the binder content. Three different lengths of fibers (10-30 mm) at fixed volume fraction were added to M30, M40 and M50 grades of concrete. The fresh and mechanical property of twelve different fiber reinforced concrete mixes was investigated. The effect of fibers on the pre cracking, post cracking behaviour of the concrete specimen was investigated using digital image processing technique and video measuring system images. Using the developed linear regression plot, empirical equations were formulated to establish relation between the compressive strength and other mechanical properties of concrete. From the study it can be concluded that the caryota fiber with rich cellulose content contributes to arrest the cracks at the initial stage of loading and prevents major crack plane in the post peak region. Fibers mainly contribute to increase the tensile property of concrete. The effect of fibers is more prominent in M30 mix concrete when compared to M40 and M50 concrete mixes
Appropriate sample size and effects of microscopic parameters on the shear strength and strain localisation of 2D cohesive-frictional granular assemblies
Full text linkGranular materials are made up of smaller particles, manifestation of microstructure results in a macroscopic response of granular material. Understanding the overall mechanical behaviour from microscopic parameters is one of the main challenges in many engineering fields including civil engineering. When modelling this kind of material by Discrete Element Model (DEM) using idealized circular grains, the effects of appropriate sample size and microscopic parameter changes have been a crucial subject. Previous research has primarily relied on the case of purely frictional granular materials. In this paper, we use DEM to investigate the appropriate sample size and the relationship between microscopic parameters and the macroscopic responses of cohesive-frictional granular assemblies by performing a series of biaxial tests. Our findings indicate that a minimum number of particles is required to balance between mechanical behaviour and computing time. In addition, through extensive parametric studies, the paper explores the impact of factors such as interparticle bonds, intergranular friction coefficients, and initial void index on the overall shear behaviour of granular assemblies. Also, the result reveals a strong correlation between shear band formation and the break field of cohesive contact (static variable) and the translations and rotations of grains (kinematic variable)
A novel application to evaluate the bridge health after retrofitting using vibration and static measurements
Full text linkThis paper proposes a novel method based on vibration and static measurement data to evaluate bridge health. This method is verified in Kenh 7 bridge. Kenh 7 Bridge is located in Long An district, Vietnam. The structural condition of the bridge was surveyed in July 2016. At that time, the girder was in good condition, whereas the deck’s concrete spalled in many areas. Then the deck was decided to punch out and be replaced with the new ones. The dynamic and static experiments of both before and after retrofitted bridges were carried out in the campaign. This research analyses the vibration data and the main girder deflection under the static load to evaluate the stiffness condition of the bridge girder, deck, and cross beam. A finite element (FE) model of the bridge is created in FE software. The Grey Wolf Optimizer algorithm will be used to update the unknown parameters. By model updating, the natural frequency and the main girder deflection differences between the experimental and the numerical results are minimized, and the concrete properties of each component are estimated. Comparing the stiffness between the before and retrofit bridge, the conclusion about the health of the Kenh 7 bridge after repair can be made. It is recommended that the cross beam should be strengthened
Using optimization algorithms to detect damages on free-free beam based on dynamic results
Full text linkThis article describes a Modal Analysis method for detecting damage in free-free beams using natural frequency data. The method involves updating a numerical model of the beam with experimental or reference natural frequencies to determine the damage location and damage index. The accuracy of the method was verified through simulations and experiments on beams with both single and double damage zones. The results demonstrate that the method is effective in detecting the damage location for single damage zone and double damage zones with the same or different damage index. However, when the two damage zones are close together, the method that updates the model through PSO optimization algorithm using the reference frequency data may produce inaccurate results. Furthermore, when using experimental frequency data for damage beams, the results indicate that the method has a damage location error of approximately 3.5% along the entire beam length, which is considered acceptable in practical applications. The natural frequency-based damage detection method described in this article offers a useful tool for the assessment of damage in free-free beams and can be effectively combined with visual inspection techniques
A Numerical Simulation Approach for Investigation of the Pressure Coefficient on the Main Building at the Hill’s Top Under the Interference.
Full text linkThe majority of the time, existing codes and standards are used to predict wind loads on structures. The criteria of these standards are based on a wind tunnel test that was done on a single building. On the other hand, buildings rarely stand alone. Wind loads on the principal building are increased or decreased as a result of interference effects caused by interfering buildings. A numerical simulation using ANSYS Fluent 2020 R1 is used in this research to investigate the impact on wind pressure on main building under the interference condition on the hill's top. The external average pressure coefficient on main building on hill’s top are determined in the presence of interfering building with varying height ratios of 0.5, 0.75, 1.0, and 1.25, and spacing to width ratios of 0.5, 1.0, 1.5, and 2.0 on 3-D hill. The pressure coefficient decreases as the height of the interfering building rises, showing an increase in the shielding effects of the structure in the vicinity. Nevertheless, when the height of the interfering building is 0.5 of the height of the main building, it is found that the shielding effect has a significant impact on the main building. Because of its placement at the top of the hill, found a significant difference in the pressure coefficient on the rear face of the main building