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Shear Strength of Circular and Rectangular Reinforced Concrete Columns
Ahmed Faleh Al-Bayati 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5
This paper presents two predictive models for the shear strength (SS) calculations of circular and rectangular reinforced concrete (RC) columns subjected to seismic load. Gene expression programming (GEP) is applied using the experimental results from the literature. The GEP models consider the influence of aspect ratio, concrete strength, axial stress, and ratios of transverse and longitudinal reinforcements. Comparisons with existing design equations evidenced the reliability of the proposed models. The parametric study and the sensitivity analysis were also performed to investigate the effect of input variables and to evaluate their contributions to the SS of RC columns.
Nadhim M. Faleh,Izz Kadhum Abboud,Amer Fadhel Nori 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.6
In this paper, analysis of thermal post-buckling behaviors of sandwich nanobeams with two layers of multi-phase magneto-electro-thermo-elastic (METE) composites have been presented considering geometric imperfection effects. Multi-phase METE material is composed form piezoelectric and piezo-magnetic constituents for which the material properties can be controlled based on the percentages of the constituents. Nonlinear governing equations of sandwich nanobeam are derived based on nonlocal elasticity theory together with classic thin beam model and an analytical solution is provided. It will be shown that post-buckling behaviors of sandwich nanobeam in thermo-electro-magnetic field depend on the constituent's percentages. Buckling temperature of sandwich nanobeam is also affected by nonlocal scale factor, magnetic field intensity and electrical voltage.
Abeer Qasim Jbur,Wael Najm Abdullah,Nadhim M. Faleh,Zahraa N. Faleh 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.2
In the present work, the vibration characteristics of sandwich nanocomposite shells, fortified with graphene platelets (GPLs) have been researched. The shell has been considered as the stadium roof shape with double curvatures under vibration due to earthquake. The nanocomposite has the matrix of concrete which is fortified with uniform or linear dispersions of GPLs. Also, the core possesses cellular type square architecture for which the effective elastic modulus has been defined in the context of relative density based relations. Based upon the classic shell strains containing two identical curvatures, the governing equations have been established and solved through differential quadrature approach. It will be seen that the vibrational frequencies rely on the core relative density, height of layers, the amount and dispersions of GPLs and even shell geometric parameters.
Fenjan, Raad M.,Faleh, Nadhim M.,Ahmed, Ridha A. Techno-Press 2020 Advances in nano research Vol.9 No.3
This research is related to nonlinear stability analysis of advanced microbeams reinforced by Graphene Platelets (GPLs) considering generic geometrical imperfections and thermal loading effect. Uniform, linear and nonlinear distributions of GPLs in transverse direction have been considered. Imperfection sensitivity of post-bucking behaviors of the microbeam to different kinds of geometric imperfections have been examined. Geometric imperfection is first considered to be identical as the first buckling mode, then a generic function is employed to consider sine-type, local-type and global-type imperfectness. Modified couple stress theory is adopted to incorporate size-dependent behaviors of the beam at micro scale. The post-buckling problem is solved analytically to derive load-amplitude curves. It is shown that post-buckling behavior of microbeam is dependent on the type geometric imperfection and its magnitude. Also, post-buckling load can be enhanced by adding more GPLs or selecting a suitable distribution for GPLs.
Fenjan, Raad M.,Ahmed, Ridha A.,Faleh, Nadhim M.,Hani, Fatima Masood Techno-Press 2020 Structural monitoring and maintenance Vol.7 No.2
Based on differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT), forced vibrations of a porous functionally graded (FG) scale-dependent beam in thermal environments have been investigated in this study. The nanobeam is assumed to be in contact with a moving point load. NSGT contains nonlocal stress field impacts together with the microstructure-dependent strains gradient impacts. The nano-size beam is constructed by functionally graded materials (FGMs) containing even and un-even pore dispersions within the material texture. The gradual material characteristics based upon pore effects have been characterized using refined power-law functions. Dynamical deflections of the nano-size beam have been calculated using DQM and Laplace transform technique. The prominence of temperature rise, nonlocal factor, strain gradient factor, travelling load speed, pore factor/distribution and elastic substrate on forced vibrational behaviors of nano-size beams have been explored.
Fenjan, Raad M.,Ahmed, Ridha A.,Faleh, Nadhim M. Techno-Press 2019 Advances in aircraft and spacecraft science Vol.6 No.4
Dynamic stability of a porous metal foam nano-dimension plate on elastic substrate exposed to bi-axial time-dependent forces has been studied via a novel 3-variable plate theory. Various pore contents based on uniform and non-uniform models have been introduced. The presented plate model contains smaller number of field variables with shear deformation verification. Hamilton's principle will be utilized to deduce the governing equations. Next, the equations have been defined in the context of Mathieu-Hill equation. Correctness of presented methodology has been verified by comparison of derived results with previous data. Impacts of static and dynamical force coefficients, non-local coefficient, foundation coefficients, pore distributions and boundary edges on stability regions of metal foam nanoscale plates will be studied.
Analyzing nonlinear vibrations of metal foam nanobeams with symmetric and non-symmetric porosities
Alasadi, Abbas A.,Ahmed, Ridha A.,Faleh, Nadhim M. Techno-Press 2019 Advances in aircraft and spacecraft science Vol.6 No.4
This article is concerned with the investigation of geometrically non-linear vibration response of refined thick porous nanobeams. To this end, non-local theory of elasticity has been adopted to provide the nanobeam formulation. Voids or pores can affect the material characteristics of the nanobeam. So, their effects have been considered in this research and also there are various void distributions. The closed form solution of the non-linear problem has been used that is adopted from previous articles. Then, it is focused on the impacts of non-local field, void distribution, void amount and geometrical properties on non-linear vibrational characteristic of a nano-size beam.
Al-Maliki, Ammar F.H.,Faleh, Nadhim M.,Alasadi, Abbas A. Techno-Press 2019 Structural monitoring and maintenance Vol.6 No.2
In present article, a size-dependent refined thick beam element has been established based upon nonlocal elasticity theory. Next, it is used to explore vibration response of porous metal foam nanobeams on elastic medium. The established beam element introduces ten degrees of freedom. Different porosity distributions called uniform, symmetric and asymmetric will be employed. Herein, introduced thick beam element contains shear deformations without using correction factors. Convergence and verification studies of obtained results from finite element method are also provided. The impacts of nonlocality factor, foundation factors, shear deformation, slenderness ratio, porosity kinds and porosity factor on vibration frequencies of metal foam nano-sized beams have been explored.
Khalaf, Basima Salman,Fenjan, Raad M.,Faleh, Nadhim M. Techno-Press 2019 Advances in materials research Vol.8 No.3
This research is devoted to analyzing mechanical-thermal post-buckling behavior of a micro-size beam reinforced with graphene platelets (GPLs) based on geometric imperfection effects. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. The micro-size beam is considered to be perfect (ideal) or imperfect. Buckling mode shape of the micro-size beam has been assumed as geometric imperfection. Modified couple stress theory has been used for describing scale-dependent character of the beam having micro dimension. Via an analytical procedure, post-buckling path of the micro-size beam has been derived. It will be demonstrated that nonlinear buckling characteristics of the micro-size beam are dependent on geometric imperfection amplitude, thermal loading, graphene distribution and couple stress effects.