Abstract
In some buildings, the lateral structural response of steel framed buildings depends on the shear walls and it is very
important to study the behavior of these elements under near-field seismic loads. The link beam in the opening of the shear wall
between two wall plates is investigated numerically in terms of behavior and effects on frames. Based on the length of the beam
and its bending and shear behavior, three types of models are constructed and analyzed, and the behavior of the frames is also
compared. The results show that by reducing the length of the link beam, the base shear forces reduce about 20%. The changes
in the length of the link beam have different effects on the degree of coupling. Increasing the length of the link beam increases
the base shear about 15%. Also, it has both, a positive and a negative effect on the degree of coupling. The increasing strength of
the coupling steel shear wall is linearly related to the yield stress of the beam materials, length, and flexural stiffness of the beam.
The use of a shorter link beam will increase the additional strength and consequently improving the behavior of the coupling
steel shear wall by reducing the stresses in this element. The link beam with large moment of inertia will also increase about
25% the additional strength and as a result the coefficient of behavior of the shear wall.
Key Words
coupled steel plate shear walls; earthquake ground motions; finite element method; mid-rise buildings;
reciprocating loads
Address
Amir Masoumi Verki:Faculty of Civil Engineering, K. N. Toosi University of Technology, No. 1346, Valiasr Street, Mirdamad Intersection, Tehran, Iran
Adolfo Preciado:Department of Habitat and Urban Development, Western Institute of Technology and Higher Education (ITESO), 45604, Tlaquepaque,
Jalisco, Mexico
Pegah Amiri Motlagh:Faculty of Mechanical Engineering, Tarbiat Modares University, Nasr, Jalal AleAhmad, Tehran, Iran
Abstract
In the present work, the flutter characteristics of porous nanocomposite cylindrical shells, reinforced with graphene
platelets (GPLs) in supersonic airflow, have been investigated. Different distributions for GPLs and porosities have been
considered which are named uniform and non-uniform distributions thorough the shell's thickness. The effective material
properties have been determined via Halpin-Tsai micromechanical model. The cylindrical shell formulation considering
supersonic airflow has been developed in the context of first-order shell and first-order piston theories. The governing equations
have been solved using Galerkin's method to find the frequency-pressure plots. It will be seen that the flutter points of the shell
are dependent on the both amount and distribution of porosities and GPLs and also shell geometrical parameters.
Key Words
flutter; graphene platelet; nanocomposite shell; porosities; porous material
Address
Mohammad Mashhour, Mohammad Reza Barati and Hossein Shahverdi:Aerospace Engineering Department and Center of Excellence in Computational Aerospace,
Amirkabir University of Technology, Tehran, 15875-4413, Iran
Abstract
The combination of replaceable and repairable properties in structures has introduced new approach called "Low
Damage Design Structures". These structural systems are designed in such a way that through self-centering, primary members
and specific connections neither suffer damage nor experience permanent deformations after being exposed to severe
earthquakes. The purpose of this study is the seismic assessment of steel moment resisting frames with the aid of rigid rocking
cores. To this end, three steel moment resisting frames of 4-, 8-, and 12-story buildings with and without rocking cores were
developed. The nonlinear static analysis and incremental dynamic analysis were performed by considering the effects of the
vertical and horizontal components of 16 strong ground motions, including far-fault and near-fault arrays. The results reveal that
rocking systems benefit from better seismic performance and energy dissipation compared to moment resisting frames and thus
structures experience a lower level of damage under higher intensity measures. The analyses show that the interstory drift in
structures equipped with stiff rocking cores is more uniform in static and dynamic analyses. A uniform interstory drift
distribution leads to a uniform distribution of the bending moment and a reduction in the structure
Key Words
incremental dynamic analysis; rocking core; seismic performance; self-centering
Address
Ali Akbari and Ali Massumi:Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, 15719-14911, Iran
Mark Grigorian:MGA Structural Engineering Consultants Inc., Glendale, California, USA
Abstract
Nonlinear free vibration and stability responses of a carbon nanotube reinforced composite beam under temperature
rising are investigated in this paper. The material of the beam is considered as a polymeric matrix by reinforced the single-walled
carbon nanotubes according to different distributions with temperature-dependent physical properties. With using the Hamilton's
principle, the governing nonlinear partial differential equation is derived based on the Euler-Bernoulli beam theory. In the
nonlinear kinematic assumption, the Von Karman nonlinearity is used. The Galerkin's decomposition technique is utilized to
discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by
using of multiple time scale method. The critical buckling temperatures, the nonlinear natural frequencies and the nonlinear free
response of the system is obtained. The effect of different patterns of reinforcement on the critical buckling temperature,
nonlinear natural frequency, nonlinear free response and phase plane trajectory of the carbon nanotube reinforced composite
beam investigated with temperature-dependent physical property.
Abstract
Although some scholars have studied the thermal post-buckling of graphene platelets strengthened metal foams
(GPLRMFs) plates, they have not considered the influence of initial geometrical imperfection. Inspired by this fact, the present
paper studies the thermal post-buckling characteristics of GPLRMFs plates with initial geometrical imperfection. Three kinds of
graphene platelets (GPLs) distribution patterns including three patterns have been considered. The governing equations are
derived according to the first-order plate theory and solved with the help of the Galerkin method. According to the comparison
with published paper, the accuracy and correctness of the present research are verified. In the end, the effects of material
properties and initial geometrical imperfection on the thermal post-buckling response of the GPLRMFs plates are examined. It
can be found that the presence of initial geometrical imperfection reduces the thermal post-buckling strength. In addition, the
present study indicates that GPL-A pattern is best way to improve thermal post-buckling strength for GPLRMFs plates, and the
presence of foams can improve the thermal post-buckling strength of GPLRMFs plates, the Foam- II and Foam- I patterns have
the lowest and highest thermal post-buckling strength. Our research can provide guidance for the thermal stability analysis of
GPLRMFs plates.
Key Words
GPLRMFs plates; graphene platelet; initial geometrical imperfection; metal foams; thermal post-buckling
Address
Yin-Ping Li, Gui-Lin She and Lei-Lei Gan:College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China
Hai-Bo Liu:College of Mechanical and Electric Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China
Abstract
Nonlinear forced vibration behaviors of sandwich plates having graphene platelets (GPL) based face sheets have
been researched in this article. Possessing low weight together with low stiffness, square honeycomb cores are mostly
constructed by aluminum. Herein, the square shaped core has been fortified by two skins of GPL-based type in such a way that
the skins have uniform and linearly graded GPL dispersions. The square shaped core has the effective material specification
according to the relative density concept. The whole formulation has been represented based upon classical plate theory (CPT)
while harmonic balance approach is applied for solving the problem and plotting the amplitude-frequency curves. The forced
vibration behaviors of such plates are influenced by square-shaped core and the relative density, skin's height and GPL
fortification.
Abstract
In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show
that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the
earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch
point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with
height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball
based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the
ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can
be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the
wind.
Key Words
football ball; free kick; numerical solution; shell model; wave propagation
Address
Xumao Cheng:1)School of Physical Education, Shanghai University of Sport, Yangpu 200082, Shanghai, China
2)Department of Sports Training, Hebei Sports University, Shijiazhuang 050041, Hebei, China
Ying Wu:School of Physical Education, Shanghai University of Sport, Yangpu 200082, Shanghai, China
Abstract
In this study, the weight and the connections type layout of low-rise eccentrically braced frame (EBF) have been
optimized based on performance-based design method. For this purpose, two objective functions were defined based on two
different aspects on rigid connections, in one of which minimization and in the other one, maximization of the number of rigid
connections was considered. These two objective functions seek to increase the area under the pushover curve, in addition to the
reduction of the weight and selection of the optimum connections type layout. The performance of these objective functions was
investigated in optimal design of a three-story eccentrically braced frame, using two meta-heuristic algorithms: Enhanced
Colliding Bodies Optimization (ECBO) and Enhanced Vibrating Particles System (EVPS). Then, the reliability indices of the
optimal designs for both objective functions were calculated for the story lateral drift limits using Monte-Carlo Simulation
(MCS) method. Based on the reliability assessment results of the optimal designs and taking the three levels of safety into
account, the final designs were selected and their specifications were compared.
Key Words
connections type layout optimization; eccentrically braced frame; performance-based design; reliability index
Address
Mohammad Ali Fathalia and Seyed Rohollah Hoseini Vaez:Department of Civil Engineering, Faculty of Engineering, University of Qom, Qom, Iran
Abstract
Geopolymer concrete production is interesting as it is an alternative to portland cement concrete. However,
workability, setting time and strength expectations limit the sustainable application of geopolymer concrete in practice. This
study aims to improve the production of geopolymer concrete to mitigate these drawbacks. The improvement in the workability
and setting time were achieved with the additional use of NaOH solution whereas an increase in the strength was gained with the
addition of recycled steel fibers from waste tires. In addition, the use of 25% basalt powder instead of fly ash and the addition of
recycled steel fibers from waste tires improved its environmental feature. The samples with steel fiber ratios ranging between
0.5% and 5% and basalt powder of 25%, 50% and 75% were tested under both compressive and flexure forces. The
compressive and flexural capacities were significantly enhanced by utilizing recycled steel fibers from waste tires. However,
decreases in these capacities were detected as the basalt powder ratio increased. In general, as the waste wire ratio increased, the
compressive strength gradually increased. While the compressive strength of the reference sample was 26 MPa, when the wire
ratio was 5%, the compressive strength increased up to 53 MPa. With the addition of 75% basalt powder, the compressive
strength decreases by 60%, but when the 3% wire ratio is reached, the compressive strength is obtained as in the reference
sample. In the sample group to which 25% basalt powder was added, the flexural strength increased by 97% when the waste
wire addition rate was 5%. In addition, while the energy absorption capacity was 0.66 kN in the reference sample, it increased to
12.33 kN with the addition of 5% wire. The production phase revealed that basalt powder and waste steel wire had a significant
impact on the workability and setting time. Furthermore, SEM analyses were performed.
Abstract
The absence of an important portion of the web plate in steel beams with multiple circular perforations, cellular
beams, causes the web plate to undergo distortions prior to and during lateral torsional buckling (LTB). The conventional LTB
equations in the codes and literature underestimate the buckling moments of cellular beams due to web distortions. The present
study is an attempt to develop analytical methods for estimating the elastic buckling moments of cellular beams. The proposed
methods rely on the reductions in the torsional and warping rigidities of the beams due to web distortions and the reductions in
the weak-axis bending and torsional rigidities due to the presence of web openings. To test the accuracy of the analytical
estimates from proposed solutions, a total of 114 finite element analyses were conducted for six different standard IPEO sections
and varying unbraced lengths within the elastic limits. These analyses clearly indicated that the LTB solutions in the AISC 360-
16 and AS4100:2020 codes overestimate the buckling loads of cellular beams within elastic limits, particularly at shorter span
lengths. The LDB solutions in the literature and the Eurocode 3 LTB solution, on the other hand, provided conservative buckling
moment estimates along the entire range of elastic buckling.
Key Words
beam stability; elastic buckling; inelastic buckling; residual stress; stability failure; web post; web
slenderness
Address
Mehmet Fethi Ertenli:Deparment of Civil Engineering, Faculty of Engineering, Karabuk University, 78050 Karabuk, Turkey
Erdal Erdal:Deparment of Computer Engineering, Faculty of Engineering and Architecture, Kirikkale University, 71450 Kirikkale, Turkey
Alper Buyukkaragoz:Deparment of Civil Engineering, Faculty of Technology, Gazi University, 06500 Ankara, Turkey
Ilker Kalkan:Deparment of Civil Engineering, Faculty of Engineering and Architecture, Kirikkale University, 71450 Kirikkale, Turkey
Ceyhun Aksoylu :Department of Civil Engineering, Konya Technical University, 42130, Konya, Turkey
