Abstract
A size dependent bending behavior of piezoelectrical flexoelectric layered perforated functionally graded (FG)
composite nanobeam rested on an elastic foundation is investigated analytically. The composite beam is composed of regularly
cutout FG core and two piezoelectric face sheets. The material characteristics is graded through the core thickness by power law
function. Regular squared cutout perforation pattern is considered and closed forms of the equivalent stiffness parameters are
derived. The modified nonlocal strain gradient elasticity theory is employed to incorporate the microstructure as well as
nonlocality effects into governing equations. The Winkler as well as the Pasternak elastic foundation models are employed to
simulate the substrate medium. The Hamiltonian approach is adopted to derive the governing equilibrium equation including
piezoelectric and flexoelectric effects. Analytical solution methodology is developed to derive closed forms for the size
dependent electromechanical as well as mechanical bending profiles. The model is verified by comparing the obtained results
with the available corresponding results in the literature. To demonstrate the applicability of the developed procedure, parametric
studies are performed to explore influences of gradation index, elastic medium parameters, flexoelectric and piezoelectric
parameters, geometrical and peroration parameters, and material parameters on the size dependent bending behavior of
piezoelectrically layered PFG nanobeams. Results obtained revealed the significant effects both the flexoelectric and
piezoelectric parameters on the bending behavior of the piezoelectric composite nanobeams. These parameters could be
controlled to improve the size dependent electromechanical as well as mechanical behaviors. The obtained results and the
developed procedure are helpful for design and manufacturing of MEMS and NEMS.
Address
Ali Alnujaie:Mechanical Engineering Department, Faculty of Engineering, Jazan University, P. O. Box 45142, Jazan, Kingdom of Saudi Arabia
Alaa A. Abdelrahman:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Abdulrahman M. Alanasari:Department of Mechanical Engineering, Faculty of Engineering, University of Business and Technology, Jeddah, Saudi Arabia
Mohamed A. Eltaher:Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia
5Department of Mechanical Design and Production, Faculty of Engineering, Zagazig University, Zagazig, Egypt
Abstract
This study experimentally investigates the flexural behavior of steel-UHPC composite slabs composed of an
innovative negative Poisson's ratio (NPR) steel plate and Ultra High Performance Concrete (UHPC) slab connected via
demountable high-strength bolt shear connectors. Eight demountable composite slab specimens were fabricated and tested under
traditional four-point bending method. The effects of loading histories (positive and negative bending moment), types of steel
plate (NPR steel plate and Q355 steel plate) and spacings of high-strength bolts (150 mm, 200 mm and 250 mm) on the flexural
behavior of demountable composite slab, including failure mode, load-deflection curve, interface relative slip, crack width and
sectional strain distribution, were evaluated. The results revealed that under positive bending moment, the failure mode of
composite slabs employing NPR steel plate was distinct from that with Q355 steel plate, which exhibited that part of highstrength bolts was cut off, part of pre-embedded padded extension nuts was pulled out, and UHPC collapsed due to
instantaneous instability and etc. Besides, under the same spacing of high-strength bolts, NPR steel plate availably delayed and
restrained the relative slip between steel plate and UHPC plate, thus significantly enhanced the cooperative deformation
capacity, flexural stiffness and load capacity for composite slabs further. While under negative bending moment, NPR steel plate
effectively improved the flexural capacity and deformation characteristics of composite slabs, but it has no obvious effect on the
initial flexural stiffness of composite slabs. Meanwhile, the excellent crack-width control ability for UHPC endowed composite
members with better durability. Furthermore, according to the sectional strain distribution analysis, due to the negative Poisson's
ratio effect and high yield strength of NPR steel plate, the tensile strain between NPR steel plate and UHPC layer held strain
compatibility during the whole loading process, and the magnitude of upward movement for sectional plastic neutral axis could
be ignored with the increase of positive bending moment.
Key Words
composite slab; cooperative deformation; flexural behavior; negative Poisson
Address
Jin-Ben Gu and Qing-Xuan Shi:College of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
Jun-Yan Wang:Key Laboratory of Advanced Civil Engineering Materials, Tongji University, Ministry of Education, Shanghai, 201804, China
Yi Tao:1)College of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
2)State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
Abstract
In this paper, the energy absorption capability of a novel cruciform composite lattice structure was evaluated
through the simulation of compression tests. For this purpose, several test samples of Polylactic acid cellular reinforced with
continuous glass fibers were prepared for compression testing using the additive manufacturing method of material extrusion.
Using a conventional path design for material extrusion, multiple debonding is probable to be occurred at the joint regions of
adjacent cells. Therefore, an innovative printing path design was proposed for the cruciform lattice structure. Afterwards, quasistatic compression tests were performed to evaluate the energy absorption behaviour of this structure. A finite element model
based on local material property degradation was then developed to verify the experimental test and extend the virtual test
method. Accordingly, different combinations of unit cell' dimensions using the design of the experiment were numerically
proposed to obtain the optimal configuration in terms of the total absorbed energy. Having brilliant energy absorption properties,
the studied cruciform lattice with its optimized unit cell dimensions can be used as an energy absorber in crashworthiness
applications. Finally, a cellular structure will be suitable with optimal behavior in crush load efficiency and high energy
absorption.
Key Words
additive manufacturing; cruciform lattice; energy absorption; FEM
Address
Hussain Gharehbaghi and Amin Farrokhabadi:Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran
Abstract
After a disaster like the catastrophic earthquake, the government have to use rapid assessment of the condition (or
damage) of bridges, buildings and other infrastructures is mandatory for rapid feedbacks, rescue and post-event management.
Many domain schemes based on the measured vibration computations, including least squares estimation and neural fuzzy logic
control, have been studied and found to be effective for online/offline monitoring of structural damage. Traditional strategies
require all external stimulus data (input data) which have been measured available, but this may not be the generalized for all
structures. In this article, a new method with unknown inputs (excitations) is provided to identify structural matrix such as
stiffness, mass, damping and other nonlinear parts, unknown disturbances for example. An analytical solution is thus constructed
and presented because the solution in the existing literature has not been available. The goals of this paper are towards access to
adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation,
implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation
results of linear and nonlinear structures show that the proposed method is able to identify structural parameters and their
changes due to damage and unknown excitations. Therefore, the goal is believed to achieved in the near future by the ongoing
development of AI and control theory.
Key Words
AI Kalman filter; benchmark structural control problem; damage resilience; fuzzy control; nonlinear
analysis; nonlinear hysteretic structure
Address
ZY Chen, Ruei-yuan Wang and Yahui Meng:Guangdong University of Petrochemical Technology, School of Science, Maoming 525000, P.R. China
Timothy Chen:School of Science, Guangdong University of Petrochemical Technology, P.R. China
Abstract
This paper is aimed at investigating the effect of multiple longitudinal stiffeners on the patch loading resistance of
slender steel plate girders. Firstly, a numerical study is conducted through geometrically and materially nonlinear analysis with
imperfections included (GMNIA), the model is validated with experimental results taken from the literature. The structural
responses of girders with multiple longitudinal stiffeners are compared to the one of girders with a single longitudinal stiffener.
Thereafter, a patch loading resistance model is developed through machine learning (ML) using symbolic regression (SR). An
extensive numerical dataset covering a wide range of bridge girder geometries is employed to fit the resistance model using SR.
Finally, the performance of the SR prediction model is evaluated by comparison of the resistances predicted using available
formulae from the literature.
Address
Carlos Graciano:Departamento de Ingenieria Civil, Universidad Nacional de Colombia, Facultad de Minas, Sede Medellin, A.A. 75267, Medellin, Colombia
Ahmet Emin Kurtoglu:Department of Civil Engineering, Igdir University, Şehit Bulent Yurtseven Campus, 76000 Igdir, Turkey
Balazs Kovesdi:Budapest University of Technology and Economics, Faculty of Civil Engineering, Department of Structural Engineering, H-1111 Budapest, Muegyetem rkp. 3, Hungary
Euro Casanova:Universidad del Bío-Bío, Departamento Ingenieria Civil y Ambiental, Avenida Collao 1202, Concepcion, Codigo Postal 4051381, Chile
Abstract
The functionally graded (FG) porous plates are usually characterized by the non-symmetric elastic modulus
distribution through the thickness so that the plate neutral surface does not coincide with the mid-surface. Nevertheless, the
conventional analysis models were mostly based on the plate mid-surface so that the accuracy of resulting numerical results is
questionable. In this context, this paper presents the neutral surface-based static and free vibration analysis of FG porous plates
and investigates the differences between the mid- and neutral surface-based analysis models. The neutral surface-based
numerical method is formulated using the (3,3,2) hierarchical model and approximated by the last introduced natural element
method (NEM). The volume fractions of metal and ceramic are expressed by the power-law function and the cosine-type
porosity distributions are considered. The proposed numerical method is demonstrated through the benchmark experiment, and
the differences between two analysis models are parametrically investigated with respect to the thickness-wise material and
porosity distributions. It is found from the numerical results that the difference cannot be negligible when the material and
porosity distributions are remarkably biased in the thickness direction.
Key Words
deflection and fundamental frequency; functionally graded porous plate; hierarchical model; mid- and
neutral surfaces; Natural element method (NEM); porosity distribution
Address
J.R. Cho:Department of Naval Architecture and Ocean Engineering, Hongik University, Sejong 30016, Korea
Abstract
Aiming at the development trend of light weight and high strength of engineering structures, this paper
experimentally investigated the seismic performance of circular-in-square high-strength concrete-filled double skin steel tubular
(HCFDST) stub columns with out-of-code width-to-thickness (B/t) ratios. Typical failure mode of HCFDST stub columns
appeared with the infill material crushing, steel fracture and local buckling of outer tubes as well as the inner buckling of inner
tubes. Subsequently, the detailed analysis on hysteretic curves, skeleton curves and ductility, energy dissipation, stiffness
degradation and lateral force reduction was conducted to reflect the influences of hollow ratios, axial compression ratios and
infill types, e.g., increasing hollow ratio from 0.54 to 0.68 and 0.82 made a slight effect on bearing capacity compared to the
ductility coefficients; the higher axial compression ratio (e.g., 0.3 versus 0.1) significantly reduced the average bearing capacity
and ductility; the HCFDST column SCFST-6 filled with concrete obviously displayed the larger initial secant stiffness with a
percentage 34.20% than the column SCFST-2 using engineered cementitious composite (ECC); increasing hollow ratios, axial
compression ratios could accelerate the drop speed of stiffness degradation. The out-of-code HCFDST stub columns with
reasonable design could behave favorable hysteretic performance. A theoretical model considering the tensile strength effect of
ECC was thereafter established and verified to predict the moment-resisting capacity of HCFDST columns using ECC. The
reported research on circular-in-square HCFDST stub columns can provide significant references to the structural application
and design.
Key Words
failure mode; high-strength CFDST stub columns; high-strength steel; out-of-code; seismic behavior;
strength model
Address
Jian-Tao Wang and Juan Wang:1)School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, P. R. China
2)Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education (XAUAT), Xi'an 710055, P. R. China
Yue Wei:Water Conservancy Bureau of Jinchuan District, Jinchang 737100, P. R. China
Yu-Wei Li and Qing Sun:Department of Civil Engineering, Xi'an Jiaotong University, Xi'an 710054, P. R. China
Abstract
To make up for the performance weaknesses of recycled aggregate concrete (RAC), expand the application
range of RAC, and alleviate the environmental problems caused by excessive exploitation of natural coarse aggregates
(NCA), this study proposes a basalt fiber-reinforced recycled aggregate concrete (BFRRAC)-filled square steel tubular
columns that combines two modification methods of steel tube and fiber, which may greatly enhance the mechanical
properties of RAC. The axial compression performance for BFRRAC-filled square steel tubular columns was reported
during this study. Seven specimens with different replacement ratios of recycled coarse aggregate (RCA), length-diameter
ratios, along with basalt fiber (BF) contents were designed as well as fabricated for performing axial compression test.
For each specimen, the whole failure process as well as mode of specimen were discovered, subsequently the load-axial
displacement curve has obtained, after which the mechanical properties was explained. A finite element analysis model
for specimens under axial compression was then established. Subsequently, based on this model, the factors affecting
axial compression performance for BFRRAC-filled square steel tubes were extended and analyzed, after which the
corresponding design suggestion was proposed. The results show that in the columns with length-diameter ratios of 5 and
8, bulging failure was presented, and the RAC was severely crushed at the bulging area of the specimen. The replacement
ratio of RCA as well as BF content little affected specimen's peak load (less than 5%). As the content of BF enhanced
from 0 kg/m3
to 4 kg/m3
, the dissipation factor and ductility coefficients increased by 10.2% and 5.6%, respectively, with
a wide range.
Key Words
axial compression test; basalt fiber; finite element analysis; recycled aggregate concrete; square steel tube
Address
Xianggang Zhang:1)School of Intelligent Construction, Wuchang University of Technology, Wuhan 430223, China
2)School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, China
Jixiang Niu and Dapeng Deng:School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454003, China
Wenlong Shen:School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China
Yajun Huang:School of Intelligent Construction, Wuchang University of Technology, Wuhan 430223, China
