Browsing by Author "Awad, Ahmed"

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Crack sliding model for non-shear FRP-reinforced slender concrete elements under shear
(Frontiers Media S.A., 2023-03) El-said, Amr; Awad, Ahmed; El-Sayed, Taha A; Özkılıç, Yasin Onuralp; Deifalla, A; Tawfik, Maged
Fiber-reinforced polymer (FRP)-reinforced concrete (RC) elements fail under one-way shear in a devastating and complicated manner with no adequate warning. In recent decades, there has been pioneering research in this area; however, there is no agreement among researchers regarding mechanicallybased models. Thus, in this current study, a plasticity-based model is developed for FRP-RC elements under shear. A selected model was firstly assessed for its accuracy, consistency, and safety against an extensive experimental database. Secondly, a plasticity-based model (i.e., crack shear sliding model) was adapted, refined, and proposed for FRP-RC elements under one-way shear. The two proposed models were found to be reliable and more accurate with respect to selected existing methods. Modeling of FRP’s axial rigidity is more consistent only under Young’s modulus with respect to the experimental database. Several concluding remarks on the selected existing models are outlined and discussed to assist the future development of these models and design codes.
Deducing Case IDs for Unlabeled Event Logs
(Springer, Cham, 2016) Bayomie, Dina; MA Helal, Iman; Awad, Ahmed; Ezat, Ehab; ElBastawissi, Ali
Event logs are invaluable sources of knowledge about the actual execution of processes. A large number of techniques to mine, check conformance and analyze performance have been developed based on logs. All these techniques require at least case ID, activity ID and the timestamp to be in the log. If one of those is missing, these techniques cannot be applied. Real life logs are rarely originating from a centrally orchestrated process execution. Thus, case ID might be missing, known as unlabeled log. This requires a manual preprocessing of the log to assign case ID to events in the log. In this paper, we propose a new approach to deduce case ID for the unlabeled event log depending on the knowledge about the process model. We provide a set of labeled logs instead of a single labeled log with different rankings. We evaluate our prototypical implementation against similar approaches.
Development of a computer based aircraft pitot-static instruments test system
(IEEE, 2015) Abdelrahman, A. A. Ahmed; Suliman, Elessaid; Awad, Ahmed
This paper is focusing on designing of a pitot-static instruments test system for aircraft using a personal computer. Pitot-static pressure was acquired using data acquisition system then sent to the computer. Then the computer calculates the corresponding values of true airspeed, indicated airspeed, vertical speed, altitude, and Mach number according to mathematical models. These values are displayed in a graphical user interface program designed using Visual Basic program. In addition to that the designed software allows the user to carry out aircraft pitot-static pressure leakage test. The developed system had been applied to check the operation of the airspeed indicator of MI-17 as an example. From experiments the airspeed indicator average error about 0.005km/h and negligible at higher speeds. The altitude indicator average error about 0.47m and increase when the altitude is above 11 km. the true air speed indicator has an average error about 0.525km/h and increase at altitudes above 12km.
Effect of hybrid-fiber- reinforcement on the shear behavior of high-strength-concrete beams
(Frontiers Media S.A., 2023-01) Awad, Ahmed; Tawfik, Maged; Deifalla, A.; Ahmad, Mahmood; Sabri, Mohanad Muayad Sabri; El-said, Amr
The shear behavior of concrete beams is highly affected by the implementation of better performance concrete. Hybrid fibers addition to concrete mixture has proven to improve the performance compared to just using single type of fiber. Thus, in this current study, the shear behavior of hybrid-fiber-reinforced-high-strength- concrete beams was investigated experimentally. In addition, the effect of the span-to-depth ratio and the transverse reinforcement ratio were examined. Results showed that, when .45% of the cement weight is replaced with polypropylene fiber and 7% of the cement weight is replaced with steel fibers, the shear strength of the beam was enhanced by 18% in comparison to the control beam. The Formation and progression of cracks were also better controlled. The behavior of hybrid-polypropylene-steel-fibers-high-strength-concrete beams was observed to be comparable to that of conventional concrete ones as the shear strength increased with the decrease in span to depth ratio or the increase in transverse reinforcing ratio. A non-linear numerical model was developed and validated using the experimental results. The shear capacities of beams were calculated using ACI, which was compared to experimental and numerical results. The ACI’s calculations were conservative when compared with the experimental or numerical results. The coefficient of variance between the ACI and experimental shear capacity results was 4.8%, while it was 9.2% between the ACI and numerical shear capacity results.
Effect of Using Lightweight Concrete on the Behavior of L and T- Beams under Combined Stresses
(azharcermjournal, 2019) Awad, Ahmed; Deifalla, Ahmed; Seleem, Hosam
This paper presents an experimental investigation for the behavior of flanged reinforced lightweight concrete (LWC) under combined stresses. LWC was obtained through the use of polystyrene foam as a partial aggregate’s replacement to reduce the concrete dry unit weight from 23.0 kN/m3 to 18.1 kN/m3. The experimental work was consisted from two phases; The first phase quantified the mechanical properties of lightweight concrete; namely the compressive and tensile strengths as well as the tension stiffening capability of the concrete mix and The second phase was concerned with testing specimens of lightweight and normal-weight concrete beams (L and T-shaped) under combined stresses for determination of the ultimate resistance, mode of failure, ultimate angle of twist, and load-deflection curve for all tested beams. The experimental program consisted of four full scale T & L beams with cross-section of (150 x 400 mm.). Two T-sections having a width of slab 550 mm and slab thickness of 150 mm, span of 1300 mm, load eccentricity of 50mm, with varying material type (LWC, and NWC). Two L-sections having a width of slab 350 mm and slab thickness of 150 mm, span of 1300 mm, load eccentricity of 50mm, with varying material type (LWC, and NWC).The main variables of this study were the material type, and the shape of cross section. The observed behavior of the light weight concrete specimens up to failure greatly encourages the use of light weight concrete in all structural elements.
Effectiveness of externally bonded CFRP strips for strengthening flanged beams under torsion: An experimental study
(Elsevier, 2013) Awad, Ahmed; Deifalla, A; Elgarhy, M
All over the world, fiber reinforced polymer (FRP) is currently being used for strengthening concrete elements, thus improving the building sustainability. The most recent report by the American Concrete Institute Committee 440 suggested that any proposed anchorage system should be heavily scrutinized before field implementation [4]. A comprehensive literature review was conducted, which showed that anchored U-jacket strips and un-anchored extended U-jacket strips were never examined for the case of RC flanged beams under significant torsion. The objective of this study is to investigate the behavior of FRP externally strengthened flanged beams subjected to torsion. Eleven beams were tested under significant torsion. Both the anchored U-jacket and the extended U-jacket strips were found to be more effective strengthening techniques compared to the un-anchored U-jacket strips and as effective as the …
FRP-RC Slabs Under Punching Shear: Assessment of Existing Models
(Springer Science and Business Media B.V., 2023-11) Tawfik, Maged; Ibrahim, Taha; Ahmad, Mahmood; Deifalla, Ahmed F; Awad, Ahmed; El-Said, Amr
The purpose of this study is to examine the punching shear behavior of concrete slabs reinforced with FRP. We compared and quickly described 21 strength models. In addition, based on overall performance, strength models were contrasted with one another in terms of the experimentally observed strength. Conclusions were made and discussed, which may help future design codes evolve more effectively, It was decided where to focus future studies. This might aid in the development of future design codes. The ACI is the least realize model, although taking into account the effects of size, dowel action, depth-to-control perimeter ratio, concrete compressive strength, and shear span-to-depth ratio.
The Mechanical Behavior of Sustainable Concrete Using Raw and Processed Sugarcane Bagasse Ash
(MDPI AG, 2022-09) El-said, Amr; Awad, Ahmed; Ahmad, Mahmood; Sabri, Mohanad Muayad Sabri; Deifalla, Ahmed Farouk; Tawfik, Maged
Sugarcane Bagasse Ash (SCBA) is one of the most common types of agricultural waste. By its availability and pozzolanic properties, sugarcane bagasse ash can be utilized as a partial replacement for cement in the production of sustainable concrete. This study experimentally investigated the impact of employing two types of sugarcane bagasse ash as a partial substitute for cement up to 30% on the compressive strength, flexural strength, and Young’s modulus of the concrete mixture. The first type of bagasse ash used was raw SCBA, which was used as it arrived from the plant, with the same characteristics, considering that it was exposed to a temperature of 600 ◦C in the boilers to generate energy. The second type of bagasse ash utilized, called processed SCBA, was produced by regrinding raw SCBA for an hour and then burning it again for two hours at a temperature of 600 ◦C. This was done to improve the pozzolanic activity and consequently the mechanical properties of the concrete mixture. The findings indicated that employing raw sugarcane bagasse ash had a detrimental effect on the mechanical characteristics of the concrete mixture but using processed sugarcane bagasse ash at a proportion of no more than 10% had a considerable effect on improving the properties of the concrete mixture. The utilization of processed SCBA up to 10% into the concrete mixture resulted in a 12%, 8%, and 8% increase in compressive strength, flexural strength, and Young’s modulus, respectively, compared to the normal concrete specimen. On the contrary, the inclusion of raw SCBA with varying content into the concrete mixture decreased compressive strength, flexural strength, and Young’s modulus by up to 50%, 30%, and 29%, respectively, compared to the normal concrete specimen. The experimental findings were validated by comparison with ACI predictions. ACI overestimated the flexural strength of SCBA concrete specimens, with a mean coefficient of difference between the ACI equation and experimental results of 22%, however, ACI underestimated the Young’s modulus of SCBA concrete specimens, with a mean coefficient of difference between the ACI equation and experimental results of −6%.
Mechanical Properties of Hybrid Steel-Polypropylene Fiber Reinforced High Strength Concrete Exposed to Various Temperatures
(Multidisciplinary Digital Publishing Institute (MDPI), 2022-06-12) Tawfik, Maged; El-said, Amr; Deifalla, Ahmed; Awad, Ahmed
Combining different types of fibers inside a concrete mixture was revealed to improve the strength properties of cementitious matrices by monitoring crack initiation and propagation. The contribution of hybrid fibers needs to be thoroughly investigated, taking into consideration a variety of parameters such as fibers type and content. In this paper, the impact of integrating hybrid steel-polypropylene fibers on the mechanical properties of the concrete mixture was investigated. Hybrid fiber-reinforced high-strength concrete mixtures were tested for compressive strength, tensile strength, and flexural strength. According to the results of the experiments, the addition of hybrid fibers to the concrete mixture improved the mechanical properties significantly, more than adding just one type of fiber for specimens exposed to room temperature. Using hybrid fibers in the concrete mixture increased compressive, tensile, and flexural strength by approximately 50%, 53%, and 46%, respectively, over just using one type of fiber. Furthermore, results showed that including hybrid fibers into the concrete mixture increased residual compressive strength for specimens exposed to high temperatures. When exposed to temperatures of 200 ◦C, 400 ◦C, and 600 ◦C, the hybrid fiber reinforced concrete specimens maintained 87%, 65%, and 42% of their initial compressive strength, respectively. In comparison, the control specimens, which were devoid of fibers, would be unable to tolerate temperatures beyond 200 ◦C, and an explosive thermal spalling occurred during the heating process.
Runtime deduction of case ID for unlabeled business process execution events
(IEEE, 2015) MA Helal, Iman; Awad, Ahmed; ElBastawissi, Ali
Events produced from business process execution need identification of process instance. With the lack of a central execution, it is hard to correlate these events to specific cases. Monitoring business processes is useful in conformance checking, compliance enforcement, risk management, and performance analysis. However, all these techniques and approaches need a set of correlated events. We present an approach to fill the gap in real life situations, between execution of unmanaged events and the stack of techniques and approaches that need labeled events at runtime to generate further analysis. This approach works on the unlabeled events, either online (as a stream of events) or offline (as a batch file of events). It deduces the case identifier for each unlabeled event, and displays the results of possible case identifiers with their rankings. Also the generated events can be filed in different event logs with different rankings to be further analyzed by other techniques and approaches
Torsion Strength of Concrete Beams with Steel Fibers, Lightweight, or FRP: Data Driven Code Appraisal
(Springer Science and Business Media B.V., 2023-11) Awad, Ahmed; Ahmed, Jawad; Deifalla, Ahmed F; Tawfik, Maged; El-Said, Amr
Despite extensive research efforts directed toward the shear and torsional behavior of concrete elements, torsion strength remains an unexplored area. Numerous new materials are being used in construction as a result of advances in concrete technology. The use of lightweight concrete, steel-fiber reinforced concrete, and FRP-reinforced concrete are all kinds of advancements. The objective of the current work is to enhance torsion strength prediction for these three aspects. A summary of a series of power equation models for torsion strength based on a massive experimental database of 346 beams tested under torsion is outlined. The model validation is discussed. The developed models are accurate while remaining simple for design purposes.