Browsing by Author "Yossef, Mostafa"

Filter results by typing the first few letters
Now showing 1 - 8 of 8
  • Analysis of multi-layers insulated sandwich panel with flexible shear connectors
    (2022-12-16) Chen, An; Bazroun, Mohammed; Yossef, Mostafa
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Insulated sandwich panel consists of face layers separated by foam insulation cores. Existing studies are mainly focused on two-layers sandwich panel. Multiple layers can also be used to increase the panels’ strength and improve their energy performance. This article presents an analytical solution for multi-layers insulated sandwich panels with flexible shear connectors, such as Fiber-Reinforced Polymer (FRP) shear connectors. For flexible shear connectors, the slip between layers leads to partial Degree of Composite Action (DCA), which is considered in the analytical solution. The analytical results are verified with Finite Element (FE) analyses. Finally, a multi-layers sandwich panel application is presented.
  • Behavior of stressed skin corrugated sheet under hydrostatic loads
    (2024-07) Abd El-Latif, Mohamed Y.; Yossef, Mostafa; Chen, An; Elsayad, Mohamed
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Water storage in buildings is an integral part of water supply, which can be used for firefighting and drinking. It can be divided into three categories: elevated, rooftop, and underground water tanks. This paper presents a novel water storage system consisting of thin-walled corrugated steel sheets, which can be installed in a multi-story building on any floor. Compared with a reinforced concrete tank, the integrated steel water tank can be fabricated and installed much faster and store freshwater more easily. To develop the system, a finite element model is developed, which is validated using the on-site measurements. Next, the model is used to conduct a parametric study to evaluate the effects of boundary conditions, panel depth, sheet thickness, trough-to-crest width ratio, and corrugation angle on the behavior of integrated steel water tanks. The model is further used to evaluate the water tank subjected to lateral diaphragm loads and report the tank stiffness under combined loads. Finally, an implementation guide for the steel tank is presented, showing the supporting system, vacuum and magnetic handling of steel panels, robotic welding techniques, and delivery. It can be concluded that the paneled steel tank can be an efficient solution for water storage inside buildings.
  • A comparative study of different methods to calculate degrees of composite action for insulated concrete sandwich panels
    (2020-06-01) Chen, An; Yossef, Mostafa; Hopkins, Paul
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Precast concrete sandwich wall panels consist of two outer wythes of precast concrete separated by a middle layer of insulation. In recent years, Fiber-Reinforced Polymer (FRP) shear connectors have been increasingly used since they have lower thermal conductivity compared to traditional steel shear connectors, which can significantly reduce thermal bridging. However, FRP shear connectors have lower stiffness, resulting in partial Degree of Composite Action (DCA), which is an important parameter to describe the structural behavior of the panels. Different methods have been proposed to calculate DCAs, including displacement method, strain method, and load method. This paper will compare and evaluate the effectiveness of these methods. A bending test was conducted on a full size of 7 m × 3 m, precast, prestressed insulated concrete sandwich panel with FRP shear connectors. A non-linear Finite Element (FE) model is created, where good correlations can be achieved between the test and FE results. The FE model is further employed to conduct a parametric study by varying the stiffness of the shear connectors. DCAs for different stiffnesses are calculated using the aforementioned three methods and the applicability and limitation of each method are investigated.
  • Deconstructable variable stiffness shear connectors in FRP deck resting on multigirder bridge system : Analytical model
    (2024-05-15) Yossef, Mostafa; Chen, An; Elsayad, Mohamed; Abd El-Latif, Mohamed Y.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Deconstructable structures offer great flexibility and reduce material waste. Fiber Reinforced-Polymer (FRP) decks resting on steel girders combine high durability, lightweight, fast construction, and deconstructablility. Composite action between the decks and girders is achieved using shear connectors. Until now, most shear connectors use adhesives or grouts, limiting their maintenance, reuse, or recycling. This paper presents a closed-form solution to analyze the behavior of an FRP deck connected to multi-girders using variable sequential stiffness shear connectors considering partial Degree of Composite Action (DCA). The analytical model, which is verified using Finite Element model and prior experimental studies, is further used to study stress and deflection for various multigirder configurations. Finally, the DCA considering variable stiffness shear connectors is presented and linked to effective width ratios, paving the way for adopting variable stiffness in bridge standards.
  • Energy-harvesting technologies within buildings
    (2023-04-30) Nerotova, Anastassia
     Insinööritieteiden korkeakoulu | Bachelor's thesis
  • Explainable artificial intelligence framework for FRP composites design
    (2024-08-01) Yossef, Mostafa; Noureldin, Mohamed; Al Kabbani, Aghyad
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Fiber-reinforced polymer (FRP) materials are integral to various industries, from automotive and aerospace to infrastructure and construction. While FRP composite design guidelines have been established, the process of obtaining the desired strength of an FRP composite demands considerable time and resources. Despite recent advancements in Machine Learning (ML) models which are commonly used as predictive models, the inherent 'black box' nature of those models poses challenges in understanding the relationship between input design parameters and output strength of the composite. Moreover, these models do not provide tools to facilitate the designing process of the composite. The current study introduces an explainable Artificial Intelligence (XAI) framework that will provide understanding for the input–output relationships of the model through SHapley Additive exPlanations (SHAP) and Partial Dependence Plots (PDPs). In addition, the framework provides for the first time a designing approach for adjusting the important design parameters to obtain the desired composite strength by the designer through utilizing an explainability technique called Counterfactual (CF). The framework is evaluated through the design of a 14-ply composite, successfully identifying critical design parameters, and specifying necessary adjustments to meet strength requirements.
  • Investigation of Combined Electronic and Ionic Thermoelectric Concrete
    (2023) Yossef, Mostafa; Mousavihashemi, Seyedabolfazl; Kallio, Tanja; Puttonen, Jari
     A3 Kirjan tai muun kokoomateoksen osa
    Thermoelectric energy is one of the promising renewable energy technologies. Research has been focused on finding new materials that have higher efficiency. While most research focuses on electronic thermoelectric materials based on solid materials, recent research also started to head towards ionic thermoelectricity utilizing the ionic conductivity of liquids and gels. Recently, more materials with p-types thermoelectric properties have been developed than n-type. More n-type thermoelectric materials are needed to be developed to produce more energy from thermoelectric modules. This paper aims to (1) illustrate the concept of combining electronic and ionic thermoelectric material properties, (2) develop an n-type thermoelectric generator using MnO2 nanopowders and cement paste which acts as a core of the sample, (3) present a novel way to compensate the strength loss through casting high strength concrete shell around the thermoelectric core. Finally, a parametric study is carried out to investigate the role of KOH, MnO2, inner core size, and the effect of temperature gradient on ionic conductivity.
  • Ionic thermoelectricity of salt-free PVA-hydrogel
    (2024-06) Yossef, Mostafa; Baniasadi, Hossein; Kallio, Tanja; Perry, Marcus; Puttonen, Jari
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    As polyvinyl alcohol (PVA) hydrogels have shown a high potential as an ionic thermoelectric generator, this paper aims to study the thermoelectric (TE) power of salt-free PVA hydrogel. Ionic thermoelectric performance, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) are measured at different relative humidities. Findings show that salt-free PVA hydrogels can achieve a relatively high Seebeck (9.26 mV K−1) using only surrounding moisture. Hydrogels with low PVA content have a more stable TE output than hydrogels with high PVA content in high relative humidity conditions. Embedded Ni-foam-CNT electrodes stabilize performance, reduce noise, and provide superior capacitance, resistance, and thermoelectric performance over direct drop-casting of CNT on hydrogels. Recommended operating relative humidity (RH) ranges between 40 % and 60 %, while recommended PVA content ranges from 10 % to 15 % mass ratio of PVA in water. The results pave the way for using PVA hydrogels as thermoelectric devices in biocompatible applications.