A model to develop the porosity of concrete as important mechanical property

Rayed Alyousef,Hisham Alabduljabbar,Abdeliazim Mustafa Mohamed,Abdulaziz Alaskar,Kittisak Jermsittiparsert,Lanh Si Ho 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.2

This numerical study demonstrates the porosity conditions and the intensity of the interactions with the aggressive agents. It is established that the density as well as the elastic modulus are correlated to ultrasonic velocity The following investigation assessed the effects of cement grade and porosity on tensile strength, flexural and compressive of Ultra High Performance Concrete (UHPC) as a numerical model in PLAXIS 2d Software. Initially, the existing strength-porosity equations were investigated. Furthermore, comparisons of the proposed equations with the existing models suggested the high accuracy of the proposed equations in predicting, cement grade concrete strength. The outcome obtained showed a ductile failure when un-corroded reinforced concrete demonstrates several bending-induced cracks transfer to the steel reinforcement. Moreover, the outcome also showed a brittle failure when wider but fewer transverse cracks occurred under bending loads. Sustained loading as well as initial pre-cracked condition during the corrosion development have shown to have significant impact on the corrosion behavior of concrete properties. Moreover, greater porosity was generally associated with lower compressive, flexural, and tensile strength. Higher cement grade, on the other hand, resulted in lower reduction in concrete strength. This finding highlighted the critical role of cement strength grade in determining the mechanical properties of concrete.

Influence of porosity and cement grade on concrete mechanical properties

Huang, Jiandong,Alyousef, Rayed,Suhatril, Meldi,Baharom, Shahrizan,Alabduljabbar, Hisham,Alaskar, Abdulaziz,Assilzadeh, Hamid Techno-Press 2020 Advances in concrete construction Vol.10 No.5

The given research focuses on examining the effect of relatively humidity (RH) and curing temperature on the hydrates as well as the porosity of calcium sulfoaluminate (CSA) cement pastes. Numerous tests, which consist of mercury intrusion porosimetry (MIP), thermosgravi metric (TG) and X-ray diffraction (XRD) were conducted. Various characterization techniques which include, scanning electron microscopy, Fourier transform microscopy along with X-ray diffraction evaluations were conducted on the samples to examine phase formation and crystallinity, morphology and microstructure along with bond formations and functional groups, respectively. During long-term study, the performance of concrete which consisted of limestone and flash-calcined was close to those from standard Portland cement concrete. Traditional classifications and methods of corrosion were widely used for the assessment of steel in concrete which may get employed to concrete which contains LC3 to recalibrate the range of polarization resistance for passitivity condition. For example, there is up to 79.5% and 146% respective flexural and compressive strengths. Moreover, they developed more advance electrical and thermo-mechanical performance with a substantial reduction in absorption of water of close to 400%. These advantages allow this research crucial to evaluate how these methods can be applied. Additionally, the research evaluates developed and more advanced cement preservation and repair techniques. The conclusion suggests concerted efforts by various stakeholders such as policy makers to enable low-carbon rates.

Elevated temperature resistance of concrete columns with axial loading

Alaskar, Abdulaziz,Alyousef, Rayed,Alabduljabbar, Hisham,Alrshoudi, Fahed,Mohamed, Abdeliazim Mustafa,Jermsittiparsert, Kittisak,Ho, Lanh Si Techno-Press 2020 Advances in concrete construction Vol.9 No.4

The influence of temperature on the material of concrete filled columns (CFCs) under axial loading has been quantitatively studied in this research. CFCs have many various advantages and disadvantages. One of the important inefficiency of classic CFCs design is the practical lack of hooped compression under the operational loads because of the fewer variables of Poisson's rate of concrete compared to steel. This is the reason why the holder tends to break away from the concrete core in elastic stage. It is also suggested to produce concrete filled steel tube columns with an initial compressed concrete core to surpass their design. Elevated temperatures have essentially reduced the strengths of steel tubes and the final capacity of CFCs exposed to fire. Thus, the computation of bearing capacity of concrete filled steel tube columns is studied here. Sometimes, the structures of concrete could be exposed to the high temperatures during altered times, accordingly, outcomes have shown a decrement in compressive-strength, then an increase with the reduction of this content. In addition, the moisture content at the minimal strength is declined with temperature rising. According to Finite Element (FE), the column performance assessment is carried out according to the axial load carrying capacities and the improvement of ductility and strength because of limitations. Self-stress could significantly develop the ultimate stiffness and capacity of concrete columns. In addition, the design equations for the ultimate capacity of concrete columns have been offered and the predictions satisfactorily agree with the numerical results. The proposed based model (FE model of PEC column) 65% aligns with the concrete exposed to high temperature. Therefore, computed solutions have represented a better perception of structural and thermal responses of CFC in fire.

Investigation on the monotonic behavior of the steel rack upright-beam column connection

Yan Cao,Rayed Alyousef,Kittisak Jermsittiparsert,Lanh Si Ho,Abdulaziz Alaskar,Hisham Alabduljabbar,Fahed Alrshoudi,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.1

The cold-formed steel storage racks are extensively employed in various industries applications such as storing products in reliable places and storehouses before distribution to the market. Racking systems lose their stability under lateral loads, such as seismic actions due to the slenderness of elements and low ductility. This justifies a need for more investigation on methods to improve their behavior and increase their capacity to survive medium to severe loads. A standardized connection could be obtained through investigation on the moment resistance, value of original rotational stiffness, ductility, and failure mode of the connection. A total of six monotonic tests were carried out to determine the behavior of the connection of straight 2.0 mm, and 2.6 mm thickness connects to 5 lug end connectors. Then, the obtained results are benched mark as the original data. Furthermore, an extreme learning machine (ELM) technique has been employed to verify and predict both moment and rotation results. Out of 4 connections, increase the ultimate moment resistance of connection by 13% and 18% for 2.0 mm and 2.6 mm upright connection, respectively.

Influence of crack on the permeability of plastic concrete

Yongqiang He,Rayed Alyousef,Abdulaziz Alaskar,Hisham Alabduljabbar,Abdeliazim Mustafa Mohamed,Nelson Maureira-Carsalade,Angel Roco-Videla,Alibek Issakhov,Hamid Assilzadeh 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.5

This study examined the relations between permeability of the concrete due to addition of new cracks. The different concrete types analyzed were standard concrete, reinforced steel fiber concrete, and reinforced concrete polypropylene fiber. In consideration of the improved polypropylene content of polypropylene fiber reinforced concrete, the crack diameter was decreased by 72-93% for up to 0.25% fiber and cracks were eliminated with 0.3% fiber inclusion. In terms of steel fiberreinforced concrete, the results showed that steel reinforcing macro fibers decrease the permeability of cracked concrete at wider crack widths. While the permeability of unreinforced concrete was the highest, 0.5% steel content resulted in lower permeability while a higher steel content concrete with 1% steel had the lowest permeability. Crack stitching phenomenon and the effect of multiple cracks may be attributed to the decrease in the permeability. With respect to normal concrete, the findings showed the crack opening displacement at the highest tension is less than 20 microns. At this loading stage, after unloading, around 80% of the displacement is restored and the residual crack opening is notably small, indicating the low impact of cracking on concrete permeability (CP) and showing that CP was increased with crack width. As a result, adding polypropylene aggregate to concrete could significantly reduce the width of crack, while adding steel fiber to concrete reduces the permeability of cracked concrete compared to normal concrete which may result in a minor crack on CP.

Hakeem: An Arabic Application Aimed to Teaching Children First Aid using Augmented Reality

Al-ajlan, Monirah,Altukhays, Wujud,Alyousef, Deema,Almansour, Aljawharah,Alsukayt, Layan,Alajlan, Halah International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.5

Children are by nature curious and enthusiastic about learning and love to explore and search for everything they see around them, but as a result of this exploration they may sometimes be exposed to dangerous situations ranging from falls to poisoning and suffocation. That is why when supporting a child's natural desire to explore the world and supporting his awareness of dangerous situations and good handling of them, helps him build a conscious scientific mind and enhance his curiosity in the natural world. It is not easy to imagine a difficult situation in which we or one of our family is in danger, unable to help ourselves or to help them in time, due to our complete ignorance of the rules of first aid. Hence the importance of learning first aid not only for the child but for the community and the world at large. "Hakeem" is an Arabic E-health educational application that aims to teach children from the age of six to eleven years first aid, in our belief that the seed of renaissance lies in the care and education of children, and the lack of Arabic content that aims to teach children first aid skills. The idea is to create a scenario in which the child is responsible for saving the person who will be in a dangerous situation using Augmented Reality (AR) technology, to increase engagement and interaction and provides a rich user experience, and according to the child's performance, he will get reward points. The game will have several levels: Beginner, Intermediate, and Hakeem, and based on the player's points he will get a title and move to the next level, and when he reaches the end, he will get the certificate.

The effect of wollastonite powder with pozzolan micro silica in conventional concrete containing recycled aggregate

Du Dinh-Cong,Mohammad. H. Keykhosravi,Rayed Alyousef,Musab N.A. Salih,Hoang Nguyen,Hisham Alabduljabbar,Abdulaziz Alaskar,Fahed Alrshoudi,Shek Poi-Ngian 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.4

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

Computational analysis of three dimensional steel frame structures through different stiffening members

Abdulaziz Alaskar,Karzan Wakil,Rayed Alyousef,Kittisak Jermsittiparsert,Lanh Si Ho,Hisham Alabduljabbar,Fahed Alrshoudi,Abdeliazim Mustafa Mohamed 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

Ground motion records are commonly used for fragility curves (FCs) developing utilized in seismic loss estimating analysis for earthquake prone zones. These records could be ‘real’, say the recorded acceleration time series or ‘simulated’ records consistent with the regional seismicity and produced by use of alternative simulation methods. This study has focused on fragility curves developing for masonry buildings through computational ‘simulated’ ground motion records while evaluating the properness of these fragilities compared to the curves generated by the use of ‘real’ records. Assessing the dynamic responses of structures, nonlinear computational time history analyses through the equivalent single degree of freedom systems have been implemented on OpenSees platform. Accordingly, computational structural analyses of multi-story 3D frame structures with different stiffening members considering soil interaction have been carried out with finite element software according to (1992) Earthquake East-West component. The obtained results have been compared to each frame regarding soil interaction. Conclusion and recommendations with the discuss of obtaining findings are presented.

Machine learning and RSM models for prediction of compressive strength of smart bio-concrete

Hassan Amer Algaifi,Suhaimi Abu Bakar,Rayed Alyousef,Abdul Rahman Mohd. Sam,Ali S. Alqarni,M.H. Wan Ibrahim,Shahiron Shahidan,Mohammed Ibrahim,Babatunde Abiodun Salami 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4

In recent years, bacteria-based self-healing concrete has been widely exploited to improve the compressive strength of concrete using different bacterial species. However, both the identification of the optimal involved reaction parameters and theoretical framework information are still limited. In the present study, both experimentally and numerical modelling using machine learning (ANN and ANFIS) and response surface methodology (RSM) were implemented to evaluate and optimse the evolution of bacterial concrete strength. Therefore, a total of 58 compressive strength tests of the concrete incorporating new bacterial species were designed using different concentrations of urea, cells concentration, calcium, nutrient and time. Based on the results, the compressive strength of the bacterial concrete improved by 16% due to the decrement of the pore percentage in the concrete skin; specifically, 5 mm from the concrete surface, compared to that of the control concrete. In the same context, both machine the learning and RSM models indicated that the optimal range of urea, calcium, nutrient and bacterial cells were (18-23 g/L), (150-350 mM), (1-3 g/L) and 2×107 cells/mL, respectively. Based on the statistical analysis, RMSE, <i>R</i>², MPE, RAE and RRSE were (0.793, 0.785), (0.985, 0.986), (1.508, 1.1), (0.11, 0.09) and (0.121, 0.12) from both the ANN and ANFIS models, respectively, while; the following values (0.839, 0.972, 1.678, 0.131 and 0.165) was obtained from RSM model, respectively. As such, it can be concluded that a high correlation and minimum error were obtained, however, machine learning models provided more accurate results compared to that of the RSM model.

Effects of heavy metal lead on differential cell counts in occupationally-exposed subjects from Saudi Arabia

Abjal P. Shaik,Abbas H. Alsaeed,Asma S. Shaik,Abdullah A. Alyousef,Vamsee K. Bammidi,Kiranmaye Sampathirao Techno-Press 2022 Advances in environmental research Vol.11 No.1

The current observational epidemiological study analyzed blood lead levels (BLLs) in occupationally exposed workers from Riyadh region, Saudi Arabia and correlated them with the alterations in the differential cell populations of the WBC panel (lymphocytes [Lym %], mixed [Mid %] cells, and neutrophils [Neu %]). In addition, we examined the effect of confounding factors and their relation to BLLs. BLLs were estimated using the LeadCare II analyzer and hematological parameters using the ADVIA 120 analyser. An inferential analysis was conducted to detect association between the observations and the subjects' clinical characateristics. A total of 132 male subjects were included in the final analyses. Based on CDC guidelines, the subjects were categorized as Group I (BLL <10 ㎍/dL; n=118) or Group II (BLL >10 ㎍/dL; n=14) with average BLLs of 4.4 ㎍/dL and 18.1 ㎍/dL, respectively (p <0.0001). The percentages of Mid cells (p <0.0001) and neutrophils (p=0.048), were significantly altered in subjects with High BLL. A regression analysis indicated that subjects > 50 years of age had significantly higher BLLs (53.2 ㎍/dL) than younger age sub-groups (p <0.0001). Age, education, and profession were significant predictors for lead toxicity. Pb exposure is a major public health issue in Saudi Arabia and calls for further investigations on the cellular and molecular effects on hematological system.