Abstract
This study aimed to develop innovative lightweight composite flooring system consisting of cold-formed steel
(CFS) and plywood with epoxy-resin adhesive connections. During the investigation, four composite floor panels were
fabricated by bonding C75.100 CFS beams with 12 mm thick Meranti plywood on bottom flange and 18 mm thick MerantiSengon plywood on top flange using epoxy-resin adhesive. These panels have dimensions of 900 mm by 2800 mm, with a
thickness of 105 mm, and were subjected to vibration, bending, and creep tests. In addition, evaluation of the floor system was
conducted to determine its compliance with the required ultimate and serviceability limit states, based on typical residential
building design loads. Numerical analysis were developed to validate the vibration and bending test results. The experimental
results for the floor system showed natural frequency of 25.65 Hz, moment capacity of 18.60 kNm, flexural stiffness of 369.96
kNm2, and 90th-day creep factor of 0.15. Numerical analysis differences compared to experimental results were in acceptable
ranges, including 0.4–10.6% for moment capacity, 3.3–5.5% for flexural stiffness, and 6.2–7.4% for natural frequency.
Following this discussion, safety factor of 6.2 was obtained from ultimate limit state evaluation. Total deflection, including 0.24
creep factor for 50-year service life, was 4.88 mm, less than 1/240 of floor span limit. The natural frequency of 25.65 Hz
exceeded the minimum comfort requirement of 8-9 Hz. The results of the investigation showed that this CFS-plywood
composite floor system was lightweight, safe, and suitable for residential buildings.
Key Words
complex networks; mathematical simulation; mechanical behavior; nanotechnology
Address
Miqdad Khosyi Akbar: Department of Civil & Environmental Engineering, Faculty of Engineering, Gadjah Mada University, Indonesia
Ali Awaludin: Department of Civil & Environmental Engineering, Faculty of Engineering, Gadjah Mada University, Indonesia
Andreas Triwiyono: Department of Civil & Environmental Engineering, Faculty of Engineering, Gadjah Mada University, Indonesia
Abstract
Active tuned mass damper (ATMD) is widely adopted as a reliable active device to protect tall buildings subjected
to earthquake excitations from severe seismic damages. Soil-structure interaction (SSI) phenomena effects on the free vibration
characteristics and the seismic responses of tall structures. This study presents the design of an adaptive sliding sector controller
(ASSC) for the active control of tall buildings equipped with an ATMD system considering the SSI effects. The ASSC technique
is designed based on the hyper-surface of the sliding mode which is surrounded by a sector and can consider the uncertainty of
system parameters. To validate the efficiency of the ASSC technique, its design is first implemented for a 40–story building
equipped with an ATMD system under an artificial earthquake excitation for different soil types. Then, the performance of the
designed ASSC technique is evaluated in mitigating the seismic responses of the structure subjected to five real earthquake
excitations considering the SSI effects. In addition, the efficiency of the designed ASSC strategy is compared against that of the
two controller techniques including proportional-integral-derivative (PID) and linear-quadratic regulator (LQR). Comparative
results demonstrate the efficiency of the ASSC strategy for the reduction of the structural responses under real earthquake
excitations.
Key Words
active tuned mass damper; adaptive control; sliding sector; soil-structure interaction; structural control
Address
Saman Saadatfar: Department of civil engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Fereshteh Emami: Department of civil engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Mohsen Khatibinia: Department of Civil Engineering, University of Birjand, Birjand, Iran
Hussein Eliasi: Department of Electrical Engineering, University of Birjand, Birjand, Iran
Abstract
In this study, a numerical simulation model is developed to investigate the load response of the low velocity impact
of unidirectional carbon fiber-reinforced polymer (CFRP) plates using the commercial explicit finite element code LS-DYNA.
The main objective is to develop an accurate computational model capable of simulating the impact procedure on the composite
structures. In the first part, the numerical simulation model is developed based on published experimental work for 300 x 150 x
2.7 mm CFRP plate consisting of 24-ply. The CFRP plate is impacted by a hemispherical steel impactor of 25.4 mm diameter
and 6.5 m/s speed to generate 40 J of impact energy. A 2D modeling approach with a single shell element is adopted. The plies
thickness and fiber-orientations are defined using PART_COMPOSITE. The linear-elastic composite material model MAT54
based on the failure criteria is used to define the unidirectional composite material, while MAT20 is used to define the impactor
material as a rigid body. Control parameters in MAT54 have been successfully calibrated to match the experimental results. The
numerical simulation results show a strong agreement with the experimental results in terms of absorbed energy, impact force,
and deflection plots. The absorbed energy value from the numerical simulation is very close to the experimental result, with a
difference of 2.86%. Only 0.85% of the impact force value is different between the numerical simulation and the experimental
result. The maximum deflection obtained is identical with the experimental result. In the second part, the developed model is
used to study the impact response and resistance of different layup configurations [i.e., Unidirectional (UD), Cross-Ply (CP),
Quasi-Isotropic (QI), Linear bio-inspired Helicoidal (LH), and nonlinear bio-inspired Fibonacci-Helicoidal (FH)]. Although the
QI and LH layup configurations do not show the lowest value for the impact force neither the absorbed energy, they produced
the lowest deflection values for the current impact condition. It can be concluded from this study that the following numerical
simulation model can be effectively utilized for the purpose of designing and analyzing innovative bio-inspired composite
structures in various configurations under different impact scenarios to study the load response.
Abstract
This study focuses on the computational stability analysis of micro-electromechanical systems (MEMS) used in
sports structures, emphasizing the impact of MEMS geometry on structural behavior. By leveraging advanced computational
models, the research explores the influence of various geometric parameters, such as aspect ratio, shape, and thickness, on the
stability and performance of MEMS components. The results reveal that small variations in geometry significantly affect the
dynamic response and overall stability, highlighting the necessity for optimized designs in sports applications. This study
provides valuable insights into the integration of MEMS technology in sports structures, enabling enhanced performance, safety,
and durability in modern sports equipment. The findings are particularly relevant for the development of smart sports gear and
wearables, where MEMS stability is crucial for real-time performance monitoring and injury prevention.
Address
Liang Xia: Department of Physical Education, Heilongjiang University of Science and Technology, Harbin 150022, Heilongjiang, China
Mostafa Habibi: 1) Universidad UTE, Facultad de Arquitectura y Urbanismo, Calle Rumipamba S/N y Bourgeois, Quito, 170147, Ecuador 2) Department of Biomaterials, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences,
Chennai, 600 077, India 3) Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam
Qinyang Li: Institute Sciences and Design of AL-Kharj, Dubai, United Arab Emirates
Abstract
This paper presents the influence of carbon nanotubes (CNTs) waviness, aspect ratio and damaged core on the
vibrational behavior of functionally graded nanocomposite sandwich beams resting on two-parameter elastic foundations. The
distributions of CNTs are considered functionally graded (FG) or uniform along the thickness of upper and bottom layers of the
sandwich beam and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory
concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-totube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler
content increases. A damage model is introduced to provide an analytical description of an irreversible rheological process that
causes the decay of the mechanical properties, in terms of engineering constants. An isotropic damage is considered for the core
of the sandwich beams. The equations of motion are derived based on Timoshenko beam theory and employing Hamilton's
principle. The problem is modeled using a semi-analytical approach composed of generalized differential quadrature method
(GDQM) and series solution adopted to solve the equations of motion. Detailed parametric studies are carried out to investigate
the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution
and boundary conditions. Also, the effects of carbon nanotubes (CNTs) waviness, CNT aspect ratio, Winkler foundation
modulus, shear elastic foundation modulus and geometrical conditions on the vibrational behavior of the sandwich structure are
studied.
Key Words
CNTs waviness and aspect ratio; damaged core; functionally graded materials; rule of mixture; sandwich
beams; two-parameter elastic foundations; vibration
Address
Lulu Wang: College of Mechanical and Electrical Engineering, Guangdong University of Science and Technology, Dongguan 523083, Guangdong, China
Hasan F. Mohsin: 1) Computer Techniques Engineering Department, Faculty of Information Technology, Imam Ja'afar Al-Sadiq University, Baghdad, Iraq, 10011
2) Computer Technical Engineering Department, College of Technical Engineering, The Islamic University, Najaf, Iraq, 54001
Pardeep Singh Bains: 1) Department of Mechanical Engineering, Faculty of Engineering and Technology, Jain (Deemed-to-be) University, Bengaluru, Karnataka560069, India 2) Department of Mechanical Engineering, Vivekananda Global University, Jaipur, Rajasthan, 303012, India
Rohit Sharma: 1) School of Engineering and Technology, Shobhit University, Gangoh, Uttar Pradesh-247341, India
2) Department of Mechanical Engineering, Arka Jain University, Jamshedpur, Jharkhand- 831001, India
Nasrin Bohlooli: Nabi Data Science & Computational Intelligence Research Co., Tehran, Iran
Abstract
The problem of concrete cracking of composite structure ill decrease of the member stiffness, and become one of
the important reasons restricting the application of composite structure. In order to solve this problem, a structural measure based
on stud connector with constraint is proposed. The feasibility of using additional steel plates to help concrete tensile in negative
bending moment region and the effectiveness of this structural measure to prevent concrete slabs from opening crack are verified
by interfacial shear performance test. The results show that the stud connector with constraint structure can restrain the cracks
within the range of 6 times the diameter of the stud, avoid longitudinal penetrating cracks of concrete slab, and give full play to
the advantages of high compressive strength of concrete. The constraint measure can effectively improve the shear stiffness of
the stud. It is proved that it is feasible to use additional steel plate to replace the concrete plate and the tensile steel bar in the
negative moment zone, and the stud connector with constraint structure can reduce the amount of transverse steel bar. A formula
for calculating shear stiffness of stud connectors with constraint structures is proposed, and a shear stiffness ratio-shear angle
curve is proposed to evaluate material utilization efficiency and shear efficiency of connectors with different length-diameter
ratios. It is suggested that the maximum elastic shear stiffness of stud connector with constraint measure. It lays a good
experimental and theoretical foundation for the engineering application of this kind of shear connector.
open access
