• Title/Summary/Keyword: impact-load

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Identification of structural systems and excitations using vision-based displacement measurements and substructure approach

  • Lei, Ying;Qi, Chengkai
    • Smart Structures and Systems
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    • 제30권3호
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    • pp.273-286
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    • 2022
  • In recent years, vision-based monitoring has received great attention. However, structural identification using vision-based displacement measurements is far less established. Especially, simultaneous identification of structural systems and unknown excitation using vision-based displacement measurements is still a challenging task since the unknown excitations do not appear directly in the observation equations. Moreover, measurement accuracy deteriorates over a wider field of view by vision-based monitoring, so, only a portion of the structure is measured instead of targeting a whole structure when using monocular vision. In this paper, the identification of structural system and excitations using vision-based displacement measurements is investigated. It is based on substructure identification approach to treat of problem of limited field of view of vision-based monitoring. For the identification of a target substructure, substructure interaction forces are treated as unknown inputs. A smoothing extended Kalman filter with unknown inputs without direct feedthrough is proposed for the simultaneous identification of substructure and unknown inputs using vision-based displacement measurements. The smoothing makes the identification robust to measurement noises. The proposed algorithm is first validated by the identification of a three-span continuous beam bridge under an impact load. Then, it is investigated by the more difficult identification of a frame and unknown wind excitation. Both examples validate the good performances of the proposed method.

Prediction of shear strength and drift capacity of corroded reinforced concrete structural shear walls

  • Yang, Zhihong;Li, Bing
    • Structural Engineering and Mechanics
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    • 제83권2호
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    • pp.245-257
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    • 2022
  • As the main lateral load resisting system in high-rise reinforced concrete structures, the mechanical performance of shear wall has a significant impact on the structure, especially for high-rise buildings. Steel corrosion has been recognized as an important factor affecting the mechanical performance and durability of the reinforced concrete structures. To investigate the effect on the seismic behaviour of corroded reinforced concrete shear wall induced by corrosion, analytical investigations and simulations were done to observe the effect of corrosion on the ultimate seismic capacity and drift capacity of shear walls. To ensure the accuracy of the simulation software, several validations were made using both non-corroded and corroded reinforced concrete shear walls based on some test results in previous literature. Thereafter, a parametric study, including 200 FE models, was done to study the influence of some critical parameters on corroded structural shear walls with boundary element. These parameters include corrosion levels, axial force ratio, aspect ratio, and concrete compressive strength. The results obtained would then be used to propose equations to predict the seismic resistance and drift capacity of shear walls with various corrosion levels.

A Study on the Physical Properties of PP/Kenaf Felt Composites According to Kenaf Fiber Compositions (케냐프 섬유 조성에 따른 PP/케냐프 펠트 복합체의 물리적 성질 연구)

  • Ku, Sun Gyo;Kim, Youn Cheol
    • Applied Chemistry for Engineering
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    • 제33권5호
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    • pp.471-476
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    • 2022
  • PP/KF felt was used to load a high content of kenaf fiber (KF) into polypropylene (PP), and polyurethane (PU) was used as a binder. In order to find an optimum composition ratio of the PU binder, the flexural strength of the PP/KF/PU felt composite according to the isocyanate and polyol ratio was evaluated. PP-g-MAH grafted with maleic anhydride (MAH) was applied as a compatibilizer. Tensile, flexural, and impact properties were evaluated to consider changes in mechanical properties of the PP/KF/PU felt composite, and the properties were improved.

Stiffening schemes for CFS built-up I-beams with large global imperfections: Capacity and behaviour

  • Dar, M. Adil;Anbarasu M.;Dar, A.R.;Islam, Naqeeb Ul;Ghowsi, Ahmad Fayeq;Carvalho, Hermes
    • Steel and Composite Structures
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    • 제42권4호
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    • pp.447-458
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    • 2022
  • Cold-formed steel (CFS) sections are thin-walled, therefore, more susceptible to different types of geometric imperfections. Global type of geometric imperfections has a significant impact on the load-carrying capacity of flexural members. This paper reports an experimental study that discusses the influence of global imperfections on the flexural response of CFS built-up I-beams composed of two lipped channels, with simply supported ends, under four-point loading. Global imperfections of magnitude over eight times the maximum permissible ones were induced in the specimens, leading to their distress. Using various simple stiffening schemes, the capacity and stiffness of the distressed specimens were improvised. The performance comparisons were made based on the maximum loads resisted, flexural stiffnesses offered, and failure modes experienced by the specimens. As experimental data on such distressed specimens are currently lacking in the literature, the test results of the present study will provide the necessary data needed by future researchers to numerically extend this study further, which will help in the development of necessary design guidelines for the same. The stiffening schemes significantly improved the structural efficiency of distressed specimens in terms of strength and stiffness, by over 60%. As a result, an effective and time-saving solution to such realistic structural engineering problems is given.

Management of the energy harvesting for MEMS/NEMS via newmark current method

  • Shang, Kun;Shan, Huafeng;Alkhalaf, Salem;Marzouki, Riadh;Khadimallah, Mohamed Amine
    • Advances in nano research
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    • 제12권6호
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    • pp.567-581
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    • 2022
  • The free and forced vibration in addition to electric energy harvesting of a piezoelectric disk resting on two-parameter foundation modeled by modified couple stress as well as Kirchhoff plate theory is probed. The governing equations and boundary conditions are obtained using Hamilton's principle. Then, the free and forced vibration are solved using numerical solutions, generalized differential quadrature method (GDQM) and Newmark-beta method. The forced vibration is resulted from a base excitation load. Also, the possible voltage which can be harvested from this system is obtained using generalized integral quadrature method. The validity of the formulation and solution procedure is confirmed using a compassion study. The impact of parameters such as length effect, inner to outer radius ratio, and foundations parameters on the free and forced vibration as well as energy harvesting is investigated in detail. This paper can be a basis for future studies in the area of piezoelectric harvesters in small scales.

Novel quasi 3D theory for mechanical responses of FG-CNTs reinforced composite nanoplates

  • Alazwari, Mashhour A.;Daikh, Ahmed Amine;Eltaher, Mohamed A.
    • Advances in nano research
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    • 제12권2호
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    • pp.117-137
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    • 2022
  • Effect of thickness stretching on free vibration, bending and buckling behavior of carbon nanotubes reinforced composite (CNTRC) laminated nanoplates rested on new variable elastic foundation is investigated in this paper using a developed four-unknown quasi-3D higher-order shear deformation theory (HSDT). The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Two new forms of CNTs reinforcement distribution are proposed and analyzed based on cosine functions. By considering the higher-order nonlocal strain gradient theory, microstructure and length scale influences are included. Variational method is developed to derive the governing equation and Galerkin method is employed to derive an analytical solution of governing equilibrium equations. Two-dimensional variable Winkler elastic foundation is suggested in this study for the first time. A parametric study is executed to determine the impact of the reinforcement patterns, nonlocal parameter, length scale parameter, side-t-thickness ratio and aspect ratio, elastic foundation and various boundary conditions on bending, buckling and free vibration responses of the CNTRC plate.

Implementing Firewall to Mitigate YOYO Attack on Multi Master Cluster Nodes Using Fail2Ban

  • Muhammad Faraz Hyder;Muhammad Umer Farooq;Mustafa Latif;Faizan Razi Khan;Abdul Hameed;Noor Qayyum Khan;M. Ahsan Siddiqui
    • International Journal of Computer Science & Network Security
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    • 제23권2호
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    • pp.126-132
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    • 2023
  • Web technology is evolving with the passage of time, from a single node server to high availability and then in the form of Kubernetes. In recent years, the research community have been trying to provide high availability in the form of multi master cluster with a solid election algorithm. This is helpful in increasing the resources in the form of pods inside the worker node. There are new impact of known DDoS attack, which is utilizing the resources at its peak, known as Yoyo attack. It is kind of burst attack that can utilize CPU and memory to its limit and provide legit visitors with a bad experience. In this research, we tried to mitigate the Yoyo attack by introducing a firewall at load-balancer level to prevent the attack from going to the cluster network.

Shear behaviour of Autoclaved Aerated Concrete (AAC) masonry walls with and without openings strengthened with welded wire mesh

  • Wanraplang Warlarpih;Comingstarful Marthong
    • Structural Engineering and Mechanics
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    • 제87권5호
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    • pp.487-498
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    • 2023
  • Unreinforced masonry (URM) buildings are extensively adopted in many of the growing nations, particularly in India. Window or door openings are required for architectural or functional reasons, which pose a threat to the building's safety. The past earthquakes have shown that the seismic capability of these structures was very weak. Strengthening these unreinforced masonry walls using welded wire mesh (WWM) is one of the most commonly and economical methods. The present experimental study investigates the impact of openings on the shear behaviour of URM walls and the effectiveness of WWM in enhancing the shear performance of masonry wall. In the experimental program 16 specimens were cast, 8 unstrengthen and 8 strengthened specimens, under 8 unstrengthen and strengthened specimens, every 2 specimens had 0%, 5%, 10%, and 15% openings and all these walls were tested under diagonal compression. The results show that the shear carrying capacity reduces as the opening percentage increases. However, strengthening the URM specimens using WWM significantly improves the peak load, shear strength, ductility, stiffness, and energy dissipation. Furthermore, the strengthening of the URM walls using WWM compensated the loss of wall capacity caused by the presence of the openings.

Automated Data Analysis of Floor Plans for the Remodeling of Apartment Housing

  • Seo, Wonseok;Kim, Seongah;Park, Junseok;Kim, Jinyoung
    • International conference on construction engineering and project management
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    • The 9th International Conference on Construction Engineering and Project Management
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    • pp.1059-1066
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    • 2022
  • In 2020, it was estimated that more than 2.4 million households in South Korea are over 30 years old. That is, more than 40% of all houses in Korea are old and that they require proper rehabilitation. The two options to improve poor living conditions are reconstruction and remodeling. Compared to reconstruction, remodeling has advantages in terms of the construction period, cost, and environmental impact. As such, the current Korean regulations are more favorable for remodeling than reconstruction. Typically, several candidate floor plans are presented in the early stages of an apartment remodeling project. Extracting information about bearing walls and other structural elements from the multiple plans to compare those plans quantitatively is one of the essential tasks during the early stage of a project. To cope with this task, an automated data extraction method for walls and slabs from before and after remodeling plans is developed. Through the developed program, load-bearing walls, non-bearing walls, slabs, and weight changes after remodeling can be analyzed and visualized in a fast and automated manner.

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Axial strength of FRP-reinforced geopolymeric concrete members: A step towards sustainable construction

  • Mohamed Hechmi El Ouni;Ali Raza;Bisma Khalid;Afzal Ahmed;Muhammad Sohail Jameel;Yasser Alashker
    • Structural Engineering and Mechanics
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    • 제86권5호
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    • pp.687-704
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    • 2023
  • This study aims to examine the structural response of glass fibre-reinforced polymer (Glass-FRP) reinforced geopolymer electronic waste aggregate concrete (GEWC) compression elements under axial compression for sustainable development. The research includes the fabrication of nine GEWC circular compression elements with different reinforcement ratios and a 3-D nonlinear finite element model using ABAQUS. The study involves a detailed parametric analysis to examine the impact of various parameters on the behavior of GEWC compression elements. The results indicate that reducing the vertical distance of glass-FRP ties improves the ductility of GEWC compression elements, and those with eight longitudinal rebars have higher axial load-carrying capacities. The finite element predictions were in good agreement with the testing results, and the put forwarded empirical model shows higher accuracy than previous models by involving the confinement effect of lateral glass-FRP ties on the axial strength of GEWC compression elements. This research work contributes to minimizing the carbon footprint of cement manufacturing and electronic waste materials for sustainable development.