Journal of Materials and Engineering Structures
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Editorial
No full textThis special issue of Journal of Materials and Engineering Structures (JMES) includes manuscripts of some of the presentations at the Forth International Conference on Sustainability in Civil Engineering (ICSCE 2022), held during 25-27 November, 2023 at Hanoi, Vietnam. We believe that all the papers published in this special issue will be an opportunity for researchers to present recent works on Sustainability in Civil Engineering field.The International Conference on Sustainability in Civil Engineering is very significant to the development of new ideas and the promotion of research into advanced in Sustainability in Civil Engineering field. ICSCE 2022 received more than 220 abstracts and 162 full papers from 14 countries and 120 full papers were accepted. According to their subject and their merit by professionals, twenty-five of the best papers presented at the ICSCE 2022 Conference have been rigorously reviewed before being accepted for this special issue.The first paper is a keynote speaker. It focuses on resource recycling, low carbon emissions, and environmental safety as means to building a sustainable environment in order to reinforce concrete works, particularly in civil engineering buildings.Six interesting articles deal with works of art and particularly bridges. Methods for detecting structural damage as part of monitoring during the operating phase are thus presented. Other methods for analyzing the delayed or dynamic responses of bridges are also covered.Five articles in this issue deal with the theme of road operation, monitoring their condition, as well as the use of construction waste or industrial waste in the construction of new roads.Five articles deal with the theme related to transport infrastructures such as railways and tunnels.Some of the other papers deal with the subject of durability relating to different themes of civil engineering, such as the performance of concrete reinforced with ash-based Geopolymer, GFRP rebars, fly ash and recycled concrete aggregate by cement.We thank all of the authors who contributed to this special issue. You can find below the important information on the forth International Conference on Sustainability in Civil Engineering such as the aim and scope and the main topics of the ICSCE2022
Evaluation of Tribological aspects of Al-Si 12 alloy and their Metal Matrix hybrid Composites produced by Liquid-metal Forging Method
Full text linkParticulate Aluminium Metal Matrix Composites (Al-MMC) have emerged as advanced engineering materials in view of their improved properties. Ceramic reinforced Al-MMC were more suitable because of being economical and exhibiting isotropic properties. Al-MMCs manufacturing methods are expensive, demand skilled and complex operations and vortex liquid metallurgy results into higher porosity. The liquid-metal forging/squeezed casting of stirred molten slurry can eliminate porosity as molten metal is pressurized during solidification forming near net shapes. During many instances, influence of process parameter (PP)s on mechanical part properties is being studied. In the present study, composites were produced using Al-Si12 alloy as base material, aluminium oxide and silicon carbide particles as reinforcements by varying the PPs. Tribological tests were conducted under dry sliding condition at room temperature showed hard reinforcements in Al alloy reduced the wear rate (WR) and increased the coefficient of friction (f) for all PPs. For PPs, increasing the squeeze pressure and decreasing the pouring and die preheating temperature resulted in a reduction of WR and f with an increase in normal load and sliding velocity. Initially f falls and then raised with an increase in normal load, but only raised with growing sliding velocity compared to Aluminium base material.
Effect of real fire and cooling systems on concrete properties
Full text linkThe impact of real fire and cooled in different environments (air and water) on ordinary strength concrete enclosing marble mining waste as coarse aggregate is discussed. The compressive strength was investigated. The experimental results reveal that, the use of different cooling regimes had significant effect on the property of concrete mixes. Thermal shock caused by the rapid cooling (immediately immersed in water after fire) showed more loss in compressive strength as compared to that of air cooling. From the experimental results it was observed that, at various temperature and cooling regimes the concrete made with marble aggregate exhibited improved performance as related to control mix. The siliceous aggregate undergo phase transformations after 573°C but the marble aggregate are stable up to 600°C. The type of cooling affects the properties of the concrete it was found from the results of this study
Study to process abnormal data for GNSS monitoring system of a long-span cable-stayed bridge in Vietnam
Full text linkGlobal Positioning System (GPS) or currently upgraded to Global Navigation Satellite System (GNSS) has been applied in many SHM systems of the super-structures, especially in the long-span bridges. A GNSS system has the ability in monitoring the global deformation of a long-span cable-stayed bridge at the millimeter level of accuracy in real-time. However, the GNSS monitoring dataset acquired from a SHM system includes various noise data such as abnormal data, missing data, and so on. This paper studies de-noising methods to detect and replace the abnormal data of a GPS monitoring dataset acquired from a real cable-stayed bridge in Vietnam. Firstly, a GPS monitoring dataset of an actual long-span cable-stayed bridge was acquired to study processing abnormal data. A scenario of abnormal data was created in a time-series GPS data, and then the Hampel identifier method was applied to detect and replace the abnormal data. The replacing data were then assessed for precision and reliability by using correlation analysis and RMSE criterion. Finally, a long-term GNSS monitoring dataset processed the abnormal data automatically. The results show, that abnormal data in GPS monitoring data can be detected and replaced with high accuracy and reliability
Damage detection for a cable-stayed Bridge under the effect of moving loads using Transmissibility and Artificial Neural Network
Full text linkArtificial Neural Network (ANN) has been widely used for Structural Health Monitoring (SHM) in the last decades. To detect damage in the structure, ANN often uses input data consisting of natural frequencies or mode shapes. However, this data is not sensitive enough to accurately identify minor structural defects. Therefore, in this study, we propose to use transmissibility to generate input data for the input layer of ANN. Transmissibility uses output signals exclusively to preserve structural dynamic properties and is sensitive to damage characteristics. To evaluate the efficiency of the proposed approach, a cable-stayed bridge with a wide variety of damage scenarios is employed. The results show that the combination of transmissibility and ANN not only accurately detect damages but also outperforms natural frequencies-based ANN in terms of accuracy and computational cost
An Appraisal on the Parameters Influencing Lime Stabilization of Soils
Full text linkSoil stabilization is a common engineering technique used to improve the physical properties of weak soil in order to achieve the desired engineering requirements. Among the various chemical stabilization techniques adopted for expansive soils, lime stabilization is the most widely adopted for controlling the swell-shrink properties of expansive soils. This study reviews the major research works carried out in the application of lime stabilization and attempts to understand various parameters that influence the effectiveness of lime stabilization. The different parameters that have been discussed include Soil Type and Mineralogy, Type, Quantity and Quality of Lime, Curing Period, Type of Curing, Curing Temperature, Moulding / Placement Water Content, Pulverization Quality, Strain Rate, pH, Organic Content, Sulphates and Extreme Conditions
Effect of Creep and Shrinkage model in calculation of long-term deflection of three-span solid slab continuous prestressed concrete bridge
Full text linkShrinkage and creep effect significantly to the long-term deflection of prestressed concrete bridge. The proper shrinkage and creep models should be developed to meet the requirements of deflection effect calculation. There are many models have been researched and developed. Each specification, such as ASSHTO, Eurocode, ACI and CEB-FIB, has their own model of shrinkage and creep by considering different input parameters. The long-term deflection calculation is also different in each specification as a result. In this paper, several shrinkage and creep models were selected and reviewed to see the differences and compare by using popular concrete grade in Vietnamese bridge construction (C40 and C45, equivalent to 40 and 45 Mpa, respectively). Those selected shrinkage and creep models are applied in calculation of deflection for a typical three-span continuous solid slab prestressed concrete bridge. The calculation results show the significant different of long-term deflection and the ASSHTO shrinkage and creep model show the biggest deflection
Simulation study on the influence of a dielectric constant gradient in the concrete on the direct wave of GPR measurements
Full text linkGround Penetrating Radar (GPR) is a non-destructive technique based on the propagation of electromagnetic wave, the propagation characteristics (speed, level of signal attenuation, ...) depend on the electromagnetic properties of the material through which it passes, where the dielectric constant of the material is one of the key parameters. Previous studies mainly based on the analysis of reflected signals to evaluate the transmission medium. Recently, the research to exploit the application of GPR direct wave (wave propagate directly in the material from the transmitting antenna to the receiving antenna) for characterization of the structural materials is becoming a matter of great interest.This paper focuses on studying on the influence of a gradient of dielectric constant in concrete on GPR direct wave, and at the same time evaluates the survey depth of GPR direct wave in concrete materials. The studying was carried out by simulation method based on GPRmax - 2D software fortwo concrete models with two gradients of dielectric constant and simultaneously with two antennas with center frequencies of 1.5 GHz and 2.6 GHz, respectively.Analysis of the obtained simulation results allows to evaluate the influence of the dielectric constant gradient on the GPR direct wave and the survey depth of the GPR direct wave.
Assessing the mechanical behaviour of adobe masonry under uniaxial compressive strength.
Full text linkEarth building has always existed on all continents; it constitutes an integral part of the cultural heritage of mankind. The present study is particularly interested in the valorisation of adobe masonry. To do this, a series of adobe units (three types: a, b and c) and adobe masonry wallets (A, B, and C) were prepared manually and infilled with 1cm thick earth mortar. In order to study the mechanical behaviour of the wallets in the laboratory, we study the mechanical behaviour of adobes and earth mortar then we apply the uniaxial loading method on the wallets. Also we present a new analytical formula which gives the mechanical properties of wallets derived from those of bricks and mortar that were determined before they were assembled. The experimental study shows that the compressive strength of wallets is 33% lower than that of adobes, and the deformations are similar to those of bricks, but they are 6 to 8 times smaller than those of mortar. The experimental mechanical properties of wallets were compared with those determined analytically. It give us results similar to the experimental ones with a ratio EManal/ EMexp equal to 1.2
Determination by analytical approach of the characteristics in free vibration of a complex asymmetric structure
Full text linkIn this paper, a new analytical calculation method is presented to study the free vibration behavior of a tall building structure with constant properties over its entire height. The proposed calculation method is based on Alembert's principle, and the continuum approach of a structure composed of walls, frames, and structural cores arranged asymmetrically according to the plane of the floor. The main idea of the present model is to associate both the coupling effect of the flexural stiffness and the shear stiffness in the differential equations governing the free vibration behavior of the structure. The analysis focuses on the determination of the free coupled vibration characteristics. According to the two orthogonal directions, the lateral bending-shear vibrations are coupled to the torsional vibrations of St-Venant. A generalized solution method is proposed using the Galerkin approach to determine the frequencies and associated mode shapes of coupled free vibration structures. The obtained results were in good agreement with those found in the literature