Numerical analysis for structure-pile-fluid-soil interaction model of fixed offshore platform

Raheem, Shehata E. Abdel,Aal, Elsayed M. Abdel,AbdelShafy, Aly G.A.,Mansour, Mahmoud H.,Omar, Mohamed Techno-Press 2020 Ocean systems engineering Vol.10 No.3

In-place analysis for offshore platforms is required to make proper design for new structures and true assessment for existing structures. In addition, ensure the structural integrity of platforms components under the maximum and minimum operating loads and environmental conditions. In-place analysis was carried out to verify the robustness and capability of structural members with all appurtenances to support the applied loads in either operating condition or storm conditions. A nonlinear finite element analysis is adopted for the platform structure above the seabed and the pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The SACS software is utilized to calculate the natural frequencies of the model and to obtain the response of platform joints according to in-place analysis then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have an important effect on the results of the in-place analysis behavior. The influence of the soil-structure interaction on the response of the jacket foundation predicts is necessary to estimate the loads of the offshore platform well and real simulation of offshore foundation for the in-place analysis. The result of the study shows that the in-place response investigation is quite crucial for safe design and operation of offshore platform against the variation of environmental loads.

Analytical and numerical algorithm for exploring dynamic response of non-classically damped hybrid structures

Raheem, Shehata E. Abdel Techno-Press 2014 Coupled systems mechanics Vol.3 No.2

The dynamic characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of hybrid structure with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as can mass and stiffness. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. A numerical algorithm capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to explore the dynamic response of hybrid tower of cable-stayed bridges: The first approach makes use of a simplified model of 2 coupled lumped masses to investigate the effects of subsystems different damping, mass ratio, frequency ratio on dynamic characteristics and equivalent modal damping; the second approach employs a detailed numerical step-by step integration procedure.

Structural performance assessment of fixed offshore platform based on in-place analysis

Raheem, Shehata E. Abdel,Aal, Elsayed M. Abdel,AbdelShafy, Aly G.A.,Mansour, Mahmoud H.,Omar, Mohamed Techno-Press 2020 Coupled systems mechanics Vol.9 No.5

In-place analysis for offshore platforms is essentially required to make proper design for new structures and true assessment for existing structures. The structural integrity of platform components under the maximum and minimum operating loads of environmental conditions is required for risk assessment and inspection plan development. In-place analyses have been executed to check that the structural member with all appurtenances robustness and capability to support the applied loads in either storm condition or operating condition. A nonlinear finite element analysis is adopted for the platform structure above the seabed and the pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The analysis includes interpretation of dynamic design parameters based on the available site-specific data, together with foundation design recommendations for in-place loading conditions. The SACS software is utilized to calculate the natural frequencies of the model and to obtain the response of platform joints according to in-place analysis then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have important effects on the results of the in-place analysis behavior. The result shows that the in-place analysis is quite crucial for safe design and operation of offshore platform and assessment for existing offshore structures.

Structural control of cable-stayed bridges under traveling earthquake wave excitation

Raheem, Shehata E Abdel Techno-Press 2018 Coupled systems mechanics Vol.7 No.3

Post-earthquake damages investigation in past and recent earthquakes has illustrated that the ground motion spatial variation plays an important role in the structural response of long span bridges. For the structural control of seismic-induced vibrations of cable-stayed bridges, it is extremely important to include the effects of the ground motion spatial variation in the analysis for design of an effective control system. The feasibility and efficiency of different vibration control strategies for the cable-stayed bridge under multiple support excitations have been examined to enhance a structure's ability to withstand earthquake excitations. Comparison of the response due to non-uniform input ground motion with that due to uniform input demonstrates the importance of accounting for spatial variability of excitations. The performance of the optimized designed control systems for uniform input excitations gets worse dramatically over almost all of the evaluation criteria under multiple-support excitations.

Effects of numerical modeling simplification on seismic design of buildings

Raheem, Shehata E Abdel,Omar, Mohamed,Zaher, Ahmed K Abdel,Taha, Ahmed M Techno-Press 2018 Coupled systems mechanics Vol.7 No.6

The recent seismic events have led to concerns on safety and vulnerability of Reinforced Concrete Moment Resisting Frame "RC-MRF" buildings. The seismic design demands are greatly dependent on the computational tools, the inherent assumptions and approximations introduced in the modeling process. Thus, it is essential to assess the relative importance of implementing different modeling approaches and investigate the computed response sensitivity to the corresponding modeling assumptions. Many parameters and assumptions are to be justified for generation effective and accurate structural models of RC-MRF buildings to simulate the lateral response and evaluate seismic design demands. So, the present study aims to develop reliable finite element model through many refinements in modeling the various structural components. The effect of finite element modeling assumptions, analysis methods and code provisions on seismic response demands for the structural design of RC-MRF buildings are investigated. where, a series of three-dimensional finite element models were created to study various approaches to quantitatively improve the accuracy of FE models of symmetric buildings located in active seismic zones. It is shown from results of the comparative analyses that the use of a calibrated frame model which was made up of line elements featuring rigid offsets manages to provide estimates that match best with estimates obtained from a much more rigorous modeling approach involving the use of shell elements.

Effects of spinal stabilization exercise with real-time ultrasound imaging biofeedback in individuals with chronic nonspecific low back pain: a pilot study

Raheem Sarafadeen,Sokunbi O. Ganiyu,Aminu A. Ibrahim 한국운동재활학회 2020 JER Vol.16 No.3

Nonlinear response of fixed jacket offshore platform under structural and wave loads

Abdel Raheem, Shehata E. Techno-Press 2013 Coupled systems mechanics Vol.2 No.1

The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under structural and wave loading is presented, the structure is discretized using the finite element method, wave plus current kinematics (velocity and acceleration fields) are generated using 5th order Stokes wave theory, the wave force acting on the member is calculated using Morison's equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-yr return period wave and must be able to survive the 100-yr return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.

Nano essential oils against the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae)

Abdel‐Raheem Mohamed,ALghamdi Huda A.,Reyad Naglaa F. 한국곤충학회 2020 Entomological Research Vol.50 No.5

The red palm weevil, Rhynchophorus ferrugineus, is the biggest pest of various palm species. The aim of this study was to evaluate the impact of the essential oils of purslane, mustard and castor (bulk and nano) on R. ferrugineus and to evaluate the oviposition deterrent effect to prevent new infestations. Prepared concentrations of essential oils (bulk and nano) were tested for their impact on R. ferrugineus larvae, pupae and adults. The most effective oil was purslane oil (bulk and nano), followed by mustard and the least effective was castor. The percent mortality of larvae was 75.2, 45.3 and 17.9% (bulk phase) and 92.5, 84.4 and 65.5% (nano phase) in purslane, mustard and castor, respectively, when treated with the high concentration. The percent mortality of adults was 67.2, 40.0 and 15.6% (bulk phase) and 83.5, 72.9 and 60.0% (nano phase) in purslane, mustard and castor, respectively, when treated with the high concentration. The number of eggs laid decreased with increasing concentration of the tested oils. Purslane essential oil showed good impact on R. ferrugineus larvae and adults followed by mustard and castor oils as bulk and as nano.

A review on influence of reactor technologies and kinetic studies for biodiesel application

Ijlal Raheem,Mohd Nurfirdaus Bin Mohiddin,Yie Hua Tan,Jibrail Kansedo,N.M. Mubarak,Mohammad Omar Abdullah,Mohd Lokman Ibrahim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.91 No.-

The increase in demand for energy has caused a clear contradiction between the supply and consumptionof these resources, which has triggered countries to divert their attention towards biodiesel. Biodieselyield and sustainability of the biodiesel production process are highly influenced by the catalyst. Homogeneous catalyst is the conventional method to produce biodiesel, but it requires larger waterconsumption to purify thefinal product while on the contrary heterogeneous catalyst does not requireexpensive utility separation cost and it can be separated from simplefiltration method. Thus, this papercomprehensively reviews the conventional and advanced biodiesel reactor technologies, particularly linkto the kinetic studies of different types of catalysts. The effects of the operating conditions on the reactortechnology with different catalysts are discussed to observe a better oil conversion. Merits andlimitations of different catalysts for biodiesel production are then compared. The kinetic studies arereviewed to compare the rate of reaction and activation energy between various types of catalysts. As thecatalyst and reactor type selection affect the transesterification reaction, it is necessary to search for thecorrect combination of catalyst and reactor to increase the efficiency of biodiesel production at a lowercost.

Inoculation of abscisic acid-producing endophytic bacteria enhances salinity stress tolerance in <i>Oryza sativa</i>

Shahzad, Raheem,Khan, Abdul Latif,Bilal, Saqib,Waqas, Muhammad,Kang, Sang-Mo,Lee, In-Jung Elsevier 2017 Environmental and experimental botany Vol.136 No.-

<P><B>Abstract</B></P> <P>Salinity hinders plant growth and results in reduced crop yield. The use of plant growth-promoting endophytic bacteria is an eco-friendly strategy to counteract such stresses and confer tolerance to the host. Endophytic bacteria have been recognized for their active role in auxin production; however, little is known about their ability to produce abscisic acid (ABA). In recent studies, the bacterial endophyte <I>Bacillus amyloliquefaciens</I> RWL-1 has been found to produce ABA, and as such, has the potential to increase plant resistance to salinity stress. Results showed that RWL-1 produced varying concentrations of ABA (0.32±0.015–0.14±0.030ngmL<SUP>−1</SUP>) under normal and saline conditions. The ability of RWL-1 to produce ABA was reduced in response to increasing salinity; however, it maintained its growth by up-regulating production of essential amino acids (glutamic acid and proline). To further investigate the potential of this endophytic bacterium, a plant-microbe interaction experiment was conducted which showed that RWL-1 inoculation significantly increased growth attributes of rice plants as compared to non-inoculated control plants under salinity stress. Micrographs also revealed active symbiosis of RWL-1 with plant roots under normal and salinity stress conditions. The essential amino acids (glutamic acid, aspartic acid, phenylalanine, proline, and cysteine) were significantly up-regulated by RWL-1 inoculation under salinity stress. In addition, the stress-sensitive endogenous ABA levels were significantly reduced, whereas the levels of endogenous salicylic acid were significantly higher in RWl-1-inoculated plants than in control plants exposed to the same level of salinity stress. The current findings suggest that the phytohormone-producing abilities of endophytic bacteria can increase plant resistance to salinity, in turn improving agricultural productivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Seed born endophytic <I>Bacillus amyloliquefaciens</I> RWL-1 was producing abscisic acid under saline conditions. </LI> <LI> RWL-1 significantly increased the <I>Oryza sativa</I> growth attributes during salinity. </LI> <LI> Increase in salinity stress tolerance to rice plants was extended by higher synthesis of amino acids during salinity. </LI> <LI> RWL-1 inoculation modulated the endogenous salicylic and abscisic acids showing improved plant physiology. </LI> </UL> </P>