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CONTENTS
Volume 27, Number 2, August 2024
 

Abstract
The prediction of seismic behavior of the existing building stock is one of the most impactful and complex problems faced by countries with frequent and intense seismic activities. Human lives can be threatened or lost, the economic life is disrupted and large amounts of monetary reparations can be potentially required. However, authorities at a regional or national level have limited resources at their disposal in order to allocate to preventative measures. Thus, in order to do so, it is essential for them to be able to rank a given population of structures according to their expected degree of damage in an earthquake. In this paper, the authors present a ranking approach, based on Machine Learning (ML) algorithms for pairwise comparisons, coupled with ad hoc ranking rules. The case study employed data from 404 reinforced concrete structures with various degrees of damage from the Athens 1999 earthquake. The two main components of our experiments pertain to the performance of the ML models and the success of the overall ranking process. The former was evaluated using the well-known respective metrics of Precision, Recall, F1-score, Accuracy and Area Under Curve (AUC). The performance of the overall ranking was evaluated using Kendall's tau distance and by viewing the problem as a classification into bins. The obtained results were promising, and were shown to outperform currently employed engineering practices. This demonstrated the capabilities and potential of these models in identifying the most vulnerable structures and, thus, mitigating the effects of earthquakes on society.

Key Words
binary classification; machine learning; ranking; seismic vulnerability

Address
Department of Civil Engineering, Democritus University of Thrace, V. Sofias 12, Xanthi, Greece

Abstract
In this paper, buckling conditions and retrofitting of cylindrical steel water storage tanks with different roof types and wall thicknesses were investigated by using finite element method. Four roof types of cylindrical steel tanks which are opentop, flat-closed, conical-closed and torispherical-closed and three wall thicknesses of 4, 6 and 8 mm were considered in FE modeling of cylindrical steel tanks. The roof shapes significantly affect load distribution on the tank shell under the seismic action. Composite FRP materials are widely used for winding thin-walled cylindrical steel structures. The retrofitting efficiency of cylindrical steel water tank is tested under the seismic loading with the externally bonded CFRP laminates. In retrofitting of cylindrical steel tank, the CFRP composite material coating method was used to improve of seismic performance of cylindrical steel tanks. ANSYS software was used to analyze the cylindrical steel tanks and maximum equivalent (von-Mises) and directional deformation were obtained. Equivalent (von-Mises) stresses significantly decreased due to the coating of the tank shell with FRP composite material. In thin-walled steel structures, excessive stress causes buckling and deformations. Therefore, retrofitting led to decrease in stress, reductions in directional and buckling deformation of the open-top, flat-closed, conicalclosed and torispherical-closed tanks.

Key Words
carbon fiber reinforced polymer (CFRP); composite material; cylindrical steel tank; retrofitting of tanks, FEM; seismic analysis

Address
Ali İhsan Çelik: Kayseri University, Tomarza Vocational High School, Kayseri, Turkey
Mehmet Metin Köse: Kahramanmaraş Sutcu Imam University, Civil Engineering, Kahramanmaraş, Turkey
Ahmet Celal Apay: Düzce University/Faculty of Art, Design and Architecture/Department of Architecture, Düzce, Turkey

Abstract
In this study, the failure mechanisms of masonry-infilled frames, commonly employed in modern construction, are analyzed at the mesoscale. An equation has been formulated to predict various failure modes of masonry-infilled frames by examining 1392 frames. The equation takes into account variables such as the height-to-width ratio, compressive strength of the masonry prism, and plastic moment capacity of the frame section. The study reveals that the compressive strength of the masonry prism and the height-to-width ratio exert the most significant influence on the lateral strength of masonry-infilled frames with a height-to-width ratio ranging from 0.2 to 1.2. The developed equation demonstrates substantial agreement with previously reported relationships, indicating high accuracy. These findings provide valuable insights into the lateral strength of infill masonry frames, which can contribute to their improved evaluation and design.

Key Words
finite element analysis; infilled frame; lateral strength; masonry infill; meso scale

Address
Sina GanjiMorad: Department of Civil engineering, Kermanshah branch, Islamic Azad University, Kermanshah, Iran
Ali Permanoon and Maysam Azadi: Department of Civil Engineering, Faculty Engineering, Razi University, Kermanshah, Iran

Abstract
The amount of wave propagation through a rubber concrete construction is the subject of the current investigation. Rubber tire waste was used to make two different types of cement mixtures. One type contains sand substitute in amounts ranging from 15% to 60% of the total volume, while the other has gravel with diameters of 3/8 and 8/15 and 15% sand in the same mixture. A wide variety of concrete forms and compositions were created, and their viscous and solid state characteristics were assessed, along with their short-, medium-, and long-term strengths. Diffusion, density, mechanical strength resistance to compressive force, and ultrasound wave propagation were also assessed. The water-to-cement ratio and plasticizer were used in this investigation. In the second part of the study, an analytical model is presented that simulates the experimental model in predicting the speed of waves and the frequencies accompanying them for this type of mixture. Higher order shear deformation beam theory for wave propagation in the rubberized concrete beam is developed, considering the bidirectional distribution, which is primarily expressed by the density, the Poisson coefficient, and Young' s modulus. Hamilton's concept is used to determine the governing equations of the wave propagation in the rubberized concrete beam structure. When the analytical and experimental results for rubber concrete beams were compared, the outcomes were very comparable. The addition of rubber gravel and sandy rubber to the mixture both resulted in a discernible drop in velocities and frequencies, according to the data.

Key Words
higher-order shear; mode frequency; mode velocity; rubberized concrete; waste rubber; wave propagation

Address
Salhi Mohamedm, Safer Omar and Hassene Daouadji Nouria: Innovative Materials Laboratory and Renewable Energies, University of Relizane, Algeria
Dahmane Mouloud: 1) Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali of Chlef, Algeria, 2) Department of Planning and Hydraulic Engineering, Higher National School of Hydraulics, Blida 9000, Algeria
Alex Li: Department of Planning and Hydraulic Engineering, Higher National School of Hydraulics, Blida 9000, Algeria
Benyahia Amar: 1) Innovative Materials Laboratory and Renewable Energies, University of Relizane, Algeria, 2) University of Saad Dahleb, Blida, Algeria
Boubekeur Toufik: 1) Innovative Materials Laboratory and Renewable Energies, University of Relizane, Algeria, 2) Tissemsilt University, BP 182, 38000, Tissemsilt, Algeria
Badache Abdelhak: 1) LABMAT Laboratory, ENPO Maurice Audin, Oran, BP 1523, El Mnaouer, Oran 31000, Algeria, 2) Department of Civil Engineering, University of Relizane, Algeria

Abstract
Friction pendulums typically suffer from poor uplift-restraining. To improve the uplift-restraining and enhance the energy dissipation capacity, this article proposed a composite isolation device based on electromagnetic forces. The device was constructed based on a remote control system to achieve semi-active control of the composite isolation device. This article introduces the theory and design of an electromagnetic chuck-friction pendulum system (ECFPS) and derives the theoretical equation for the ECFPS based on Maxwell' s electromagnetic attraction equation to construct the proposed model. By conducting 1:3 scale tests on the electromagnetic device, the gaps between the practical, theoretical, and simulation results were analyzed, and the accuracy and effectiveness of the theoretical equation for the ECFPS were investigated. The hysteresis and uplift-restraining performance of ECFPS were analyzed by adjusting the displacement amplitude, vertical load, and input current of the simulation model. The data obtained from the scale test were consistent with the theoretical and simulated data. Notably, the hysteresis area of the ECFPS was 35.11% larger than that of a conventional friction pendulum. Lastly, a six-story planar frame structure was established through SAP2000 for a time history analysis. The isolation performances of ECFPS and FPS were compared. The results revealed that, under horizontal seismic action, the horizontal seismic response of the bottom layer of the ECFPS isolation structure is greater than that of the FPS, the horizontal vibration response of the top layer of the ECFPS isolation structure is smaller than that of the FPS, and the axial force at the bottom of the columns of the ECFPS isolation structure is smaller than that of the FPS isolation structure. Therefore, the reliable uplift-restraining performance is facilitated by the electromagnetic force generated by the device.

Key Words
friction pendulum system, hysteretic performance, multi-physics field coupling, uplift-restraining performance

Address
School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China

Abstract
Studying the propagation characteristics of waves in circular plates has important engineering value. In this paper, graphene sheet reinforced foam (GPLRMF) circular plates are taken as the research object, and the propagation characteristics of shear and bending waves in the structure are analyzed. In the process of research, we assume that the material properties are closely related to temperature, and use the first-order shear deformation theory (FSDT) to establish the dynamic model of GPLRMF circular plates. Considering the simply supported boundary conditions, the relationship between phase velocity/group velocity and wave number was obtained through Laplace transform. Subsequently, the influence of material and geometric parameters on wave propagation characteristics was analyzed, and the results showed that the porosity coefficient and temperature had a significant impact on the characteristics of wave propagation in circular plates.

Key Words
circular plates; graphene platelets; thermal effect; wave propagation

Address
College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

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