Abstract
In this paper, frequency analysis of curved functionally graded (FG) nanobeam by consideration of deepness effect
has been studied. Differential transform method (DTM) has been used to obtain frequency responses. The nonlocal theory of
Eringen has been applied to consider nanoscales. Material properties are supposed to vary in radial direction according to powerlaw distribution. Differential equations and related boundary conditions have been derived using Hamilton`s principle. Finally,
by consideration of nonlocal theory, the governing equations have been derived. Natural frequencies have been obtained using
semi analytical method (DTM) for different boundary conditions. In order to study the effect of deepness, the deepness term is
considered in strain field. The effects of the gradient index, radius of curvature, the aspect ratio, the nonlocal parameter and
interaction of aforementioned parameters on frequency value for different boundary conditions such as clamped-clamped (C-C),
clamped-hinged (C-H), and clamped-free (C-F) have been investigated. In addition, the obtained results are compared with the
results in previous literature in order to validate present study, a good agreement was observed in the present results.
Key Words
deepness effect; Differential Transform Method (DTM); FG curved beam; free vibration; nonlocal theory
Address
S. A. H. Hosseini:Department of Industrial, Mechanical and Aerospace Engineering, Buein Zahra Technical University, Buein Zahra, Qazvin, Iran
O. Rahmani:Smart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
Abstract
To investigate the seismic behavior of steel slag self-stressing concrete–filled circular steel tubular (SSSCFCST)
columns, 14 specimens were designed, namely, 10 SSSCFCST columns and four ordinary steel slag (SS) concrete (SSC)–filled
circular steel tubular (SSCFCST) columns. Comparative tests were conducted under low reversed cyclic loading considering
various parameters, such as the axial compression ratio, diameter–thickness ratio, shear–span ratio, and expansion ratio of SSC.
The failure process of the specimens was observed, and hysteretic and skeleton curves were obtained. Next, the influence of
these parameters on the hysteretic behavior of the SSSCFCST columns was analyzed. The self stress of SS considerably
increased the bearing capacity and ductility of the specimens. Results indicated that specimens with a shear–span ratio of 1.83
exhibited compression bending failure, whereas those with shear–span ratios of 0.91 or 1.37 exhibited drum-shaped cracking
failure. However, shear–bond failure occurred in the nonloading direction. The stiffness of the falling section of the specimens
decreased with increasing shear–span ratio. The hysteretic curves exhibited a weak pinch phenomenon, and their shapes evolved
from a full shuttle shape to a bow shape during loading. The skeleton curves of the specimens were nearly complete, progressing
through elastic, elastoplastic, and plastic stages. Based on the experimental study and considering the effects of the SSC
expansion rate, shear–span ratio, diameter–thickness ratio, and axial compression ratio on the seismic behavior, a peak
displacement coefficient of 0.91 was introduced through regression analysis. A simplified method for calculating load–
displacement skeleton curves was proposed and loading and unloading rules for SSSCFCST columns were provided. The load–
displacement restorative force model of the specimens was established. These findings can serve as a guide for further research
and practical application of SSSCFCST columns.
Abstract
In this study, the natural frequencies of Functional Graded Materials (FGM) plates are predicted using Artificial
Neural Network (ANN). A model based on Third-order Shear Deformation Theory (TSDT) and FEM is used to train the ANN
model. Different training methods are tested to simulate input and output dependency. As this is a parametric model, several
architectures and optimization algorithms were tested. The proposed model allows us to minimize the CPU time to evaluate
candidate material properties for FGM plate material selection and demonstrate their influence on dynamic behavior.
Consequently, the time required for the FGM design process (candidate materials for material selection) and the geometric
optimization of the FGM structure would remain reasonable. The ANN model can help industries to produce FGM plates with
good mechanical properties of the selected materials. I addition, this model can be used to directly predict vibration behavior by
testing a large number of FGM plates, representing all possible combinations of metals and ceramics in today's industry, without
having to solve any eigenvalue problems.
Key Words
artificial neural networks, CPU time, finite element method, natural frequencies, third order shear
deformation theory
Address
Mohamed Janane Allah, Saad Hassouna and Abdelaziz Timesli:Hassan II University of Casablanca, National Higher School of Arts and Crafts of Casablanca,
AICSE Laboratory, 20670 Casablanca, Morocco
Rachid Aitbelale:University of Chouaïb Doukkali, Faculty of sciences, Laboratory of Catalysis and Corrosion of Materials, El Jadida, Morocco
Abstract
Due to the steadily declining supply of natural coarse aggregates, the concrete industry has shifted to substituting
coarse aggregates generated from byproducts and industrial waste. Oil palm shell is a substantial waste product created during
the production of palm oil (𝑂𝑃𝑆). When considering the usage of 𝑂𝑃𝑆𝐶, building engineers must consider its uniaxial
compressive strength (𝑈𝐶𝑆). Obtaining 𝑈𝐶𝑆 is expensive and time-consuming, machine learning may help. This research
established five innovative hybrid 𝐴𝐼 algorithms to predict 𝑈𝐶𝑆. Aquila optimizer (𝐴𝑂) is used with methods to discover
optimum model parameters. Considered models are artificial neural network (𝐴𝑂 − 𝐴𝑁𝑁), adaptive neuro-fuzzy inference
system (𝐴𝑂 − 𝐴𝑁𝐹𝐼𝑆), support vector regression (𝐴𝑂 − 𝑆𝑉𝑅), random forest (𝐴𝑂 − 𝑅𝐹), and extreme gradient boosting
(𝐴𝑂 − 𝑋𝐺𝐵). To achieve this goal, a dataset of 𝑂𝑃𝑆-produced concrete specimens was compiled. The outputs depict that all
five developed models have justifiable accuracy in 𝑈𝐶𝑆 estimation process, showing the remarkable correlation between
measured and estimated 𝑈𝐶𝑆 and models' usefulness. All in all, findings depict that the proposed 𝐴𝑂 − 𝑋𝐺𝐵 model
performed more suitable than others in predicting 𝑈𝐶𝑆 of 𝑂𝑃𝑆𝐶 (with 𝑅
2
, 𝑅𝑀𝑆𝐸, 𝑀𝐴𝐸, 𝑉𝐴𝐹 and 𝐴15−index at 0.9678,
1.4595, 1.1527, 97.6469, and 0.9077). The proposed model could be utilized in construction engineering to ensure enough
mechanical workability of lightweight concrete and permit its safe usage for construction aims.
Key Words
AO-XGB; green construction; hybrid data mining; oil palm shell; uniaxial compressive strength
Address
Yipeng Feng:1)School of Civil Engineering and Architecture, Guangxi University, Nanning 530004, P.R. China
2)Guangxi Ansheng Testing Co Ltd, Bldg. D,12 Nahong Ave, Nanning 530033, Guangxi, P.R. China
Jiang Jie:School of Civil Engineering and Architecture, Guangxi University, Nanning 530004, P.R. China
Amir Toulabi:Faculty of Civil, Water, and Environmental Engineering, Shahid Beheshti University, Tehran, Iran
Abstract
In the context of finite element method, a computational simulation is presented to study and analyze the dynamic
behavior of regularly perforated functionally graded rotating beam for the first time. To investigate the effect of perforation
configurations, both regular circular and squared perforation patterns are studied. To explore impacts of graded material
distributions, both axial and transverse gradation profiles are considered. The material characteristics of graded materials are
assumed to be smoothly and continuously varied through the axial or the thickness direction according the nonlinear power
gradation law. A computational finite elements procedure is presented. The accuracy of the numerical procedure is verified and
compared. Resonant frequencies, axial displacements as well as internal stress distributions throughout the perforated graded
rotating cantilever beam are studied. Effects of material distributions, perforation patterns, as well as the rotating beam speed are
investigated. Obtained results proved that the graded material distribution has remarkable effects on the dynamic performance.
Additionally, circular perforation pattern produces more softening effect compared with squared perforation configuration thus
larger values of axial displacements and maximum principal stresses are detected. Moreover, squared perforation provides smaller
values of nondimensional frequency parameters at most of vibration modes compared with circular pattern.
Key Words
axial and transverse gradation profiles; computational finite elements procedure; dynamic behavior;
functionally graded; perforation patterns; regularly perforated functionally graded beams; stress distribution
Address
Alaa A. Abdelrahman:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Hanaa E. Abd-El-Mottaleb, Mohamed G. Elblassy and Eman A. Elshamy:Department of structural Engineering, Faculty of Engineering, Zagazig university, P.O. Box 44519, Zagazig, Egypt
Abstract
In recent years, Carbon Fibre Reinforced Plastic (CFRP) strengthening is found to be one of the best methods to
strengthen steel structures. The fibrous bond can also influence the vibration characteristics of the strengthened element apart from
its static strength enhancement property. The main objective of this study is to understand the influence of CFRP strengthening on
the dynamic Behaviour of Thin-Webbed Castellated Beams (TWCBs). A detailed experimental investigation was carried out on five
sets of beams with varying parameters such as domination of shear (Shear Dominant, Moment Dominant and Moment and Shear
Dominant), sectional classification (Plastic and Semi-compact) and perforation geometries (ho/dwratio 0.65 and e/ho ratio 0.3). Free
vibration analysis was carried out by exciting the simply supported TWCBs with an impact force generated by a ball dropped from
a specific height. Logarithmic decrement method was used to obtain the damping ratio and natural frequencies of vibration were
found by Fast Fourier Transform (FFT). Natural frequency showed an increase in a range of 10.5 - 55% for the different sets of
castellated beams. An increase of 62.30% was noted in the damping ratio of TWCBs after strengthening which is an indication of
improvement in the vibration characteristics of the beam.
Address
Cyril Thomas Antony Raj: School of Civil Engg., SASTRA Deemed to be University, Thanjavur - 613401, Tamil Nadu, India
Jyothis Paul Elanhikuzhy and Baskar Kaliyamoorthy:Department of Civil Engg., National Institute Technology Tiruchirappalli, Tiruchirappalli – 620015, Tamil Nadu, India
Abstract
In order to fully reflect variation characteristics of composite concrete dam health state, the monitoring data is
applied to diagnose composite concrete dam health state. Composite concrete dam lesion development to wreckage is a
precursor, and its health status can be judged. The monitoring data are generally non-linear and unsteady time series, which
contain chaotic information that cannot be characterized. Thus, it could generate huge influence for the construction of
monitoring models and the formulation of corresponding health diagnostic indicators. This multi-scale diagnosis process is from
point to whole. Chaotic characteristics are often contained in the monitoring data. If chaotic characteristics could be extracted for
reflecting concrete dam health state and the corresponding diagnostic indicators will be formulated, the theory and method of
diagnosing concrete dam health state can be huge improved. Therefore, the chaotic characteristics of monitoring data are
considered. And, the extracting method of the chaotic components is studied from monitoring data based on fuzzy dynamic
cross-correlation factor method. Finally, a method is proposed for formulating composite concrete dam health state indicators.
This method can effectively distinguish chaotic systems from deterministic systems and reflect the health state of concrete dam
in service.
Key Words
concrete dam; fuzzy dynamic; haotic characteristics; health diagnosis; monitoring data
Address
Hao Gu:1)College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
2)Cooperative Innovation Center for Water Safety and Hydro Science, Hohai University, Nanjing 210098, China
3)National Key Laboratory of Water Disaster Prevention, Nanjing 210098, China
Zihan Jiang:College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Meng Yang:1)Nanjing Hydraulic Research Institute, Nanjing 210029, China
2)Cooperative Innovation Center for Water Safety and Hydro Science, Hohai University, Nanjing 210098, China
3)National Key Laboratory of Water Disaster Prevention, Nanjing 210098, China
Li Shi:China Electric Construction Group Northwest Survey and Design Institute Company, Xi'an, 710065, China
Xi Lu:China Electric Construction Group Northwest Survey and Design Institute Company, Xi'an, 710065, China
Wenhan Cao:College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Kun Zhou:College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Lei Tang:Nanjing Hydraulic Research Institute, Nanjing 210029, China
Abstract
This paper aims to investigate the free vibration analysis of FG plates, taking into account the effects of even and
uneven porosity. The study employs the Hellinger-Reisner functional and obtains the element's bending stress and membrane
stress fields from the analytical solution of the governing equations of the thick plate and plane problem, respectively. The
displacement field serves as the second independent field. While few articles on free vibration analysis of circular plates exist,
this paper investigates the free vibration of both rectangular and circular plates. After validating the proposed element, the paper
investigates the effects of porosity distributions on the natural frequency of the FG porous plate. The study calculates the natural
frequency of thin and thick bending plates with different aspect ratios and support conditions for various porosity and volume
fraction index values. The study uses three types of porosity distributions, X, V, and O, for the uneven porosity distribution case.
For O and V porosity distribution modes, porosity has a minor effect on the natural frequency for both circular and rectangular
plates. However, in the case of even porosity distribution or X porosity distribution, the effect of porosity on the natural
frequency of circular and rectangular plates increases with an increase in the volume fraction index.
Key Words
circular and rectangular plates; Hellinger-Reisner functional; free vibration; functionally graded porous
plate; thick plate governing equation
Address
Majid Yaghoobi and Mohsen Sedaghatjo:Civil Engineering and Architecture Department, Engineering Faculty, University of Torbat Heydarieh, Torbat Heydarieh, Iran
Mohammad Karkon:Civil Engineering Department, Larestan Branch Islamic Azad University, Larestan, Iran
Lazreg Hadji:Civil Engineering Department, Faculty of Applied Sciences, University of Tiaret, Tiaret, Algeria
