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23 pages, 2779 KiB  
Article
Seismic Response Analysis of a Six-Story Building in Sofia Using Accelerograms from the 2012 Mw5.6 Pernik Earthquake
by Lyubka Pashova, Emil Oynakov, Ivanka Paskaleva and Radan Ivanov
Appl. Sci. 2025, 15(15), 8385; https://doi.org/10.3390/app15158385 - 28 Jul 2025
Viewed by 239
Abstract
On 22 May 2012, a magnitude Mw 5.6 earthquake struck the Pernik region of western Bulgaria, causing structural damage in nearby cities, including Sofia. This study assesses the seismic response of a six-story reinforced concrete building in central Sofia, utilizing real accelerogram data [...] Read more.
On 22 May 2012, a magnitude Mw 5.6 earthquake struck the Pernik region of western Bulgaria, causing structural damage in nearby cities, including Sofia. This study assesses the seismic response of a six-story reinforced concrete building in central Sofia, utilizing real accelerogram data recorded at the basement (SGL1) and sixth floor (SGL2) levels during the earthquake. Using the Kanai–Yoshizawa (KY) model, the study estimates inter-story motion and assesses amplification effects across the structure. Analysis of peak ground acceleration (PGA), velocity (PGV), displacement (PGD), and spectral ratios reveals significant dynamic amplification of peak ground acceleration and displacement on the sixth floor, indicating flexible and dynamic behavior, as well as potential resonance effects. The analysis combines three spectral techniques—Horizontal-to-Vertical Spectral Ratio (H/V), Floor Spectral Ratio (FSR), and the Random Decrement Method (RDM)—to determine the building’s dynamic characteristics, including natural frequency and damping ratio. The results indicate a dominant vibration frequency of approximately 2.2 Hz and damping ratios ranging from 3.6% to 6.5%, which is consistent with the typical damping ratios of mid-rise concrete buildings. The findings underscore the significance of soil–structure interaction (SSI), particularly in sedimentary basins like the Sofia Graben, where localized geological effects influence seismic amplification. By integrating accelerometric data with advanced spectral techniques, this research can enhance ongoing site-specific monitoring and seismic design practices, contributing to the refinement of earthquake engineering methodologies for mitigating seismic risk in earthquake-prone urban areas. Full article
(This article belongs to the Special Issue Seismic-Resistant Materials, Devices and Structures)
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22 pages, 12919 KiB  
Article
Vibration Control of Deepwater Offshore Platform Using Viscous Dampers Under Wind, Wave, and Earthquake
by Kaien Jiang, Huiyang Li, Guoer Lv, Lizhong Wang, Lilin Wang and Huafeng Yu
J. Mar. Sci. Eng. 2025, 13(7), 1197; https://doi.org/10.3390/jmse13071197 - 20 Jun 2025
Viewed by 311
Abstract
This study investigates the use of viscous dampers (VDs) to reduce the vibration of a deepwater offshore platform under joint wind, wave, and earthquake action. A finite element model was established based on the Opensees software (version 3.7.1), incorporating soil–structure interaction simulated by [...] Read more.
This study investigates the use of viscous dampers (VDs) to reduce the vibration of a deepwater offshore platform under joint wind, wave, and earthquake action. A finite element model was established based on the Opensees software (version 3.7.1), incorporating soil–structure interaction simulated by the nonlinear Winkler springs and simulating hydrodynamic loads via the Morison equation. Turbulent wind fields were generated using the von Kármán spectrum, and irregular wave profiles were synthesized from the JONSWAP spectrum. The 1995 Kobe earthquake record served as seismic input. The time-history dynamic response for the deepwater offshore platform was evaluated under two critical scenarios: isolated seismic excitation and the joint action of wind, wave, and seismic loading. The results demonstrate that VDs configured diagonally at each structural level effectively suppress platform vibrations under both isolated seismic and wind–wave–earthquake conditions. Under seismic excitation, the VD system reduced maximum deck acceleration, velocity, displacement, and base shear force by 9.95%, 22.33%, 14%, and 31.08%, respectively. For combined environmental loads, the configuration achieved 15.87%, 21.48%, 13.51%, and 34.31% reductions in peak deck acceleration, velocity, displacement, and base shear force, respectively. Moreover, VD parameter analysis confirms that increased damping coefficients enhance control effectiveness. Full article
(This article belongs to the Section Ocean Engineering)
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14 pages, 23275 KiB  
Article
Response of a Structure Isolated by a Coupled System Consisting of a QZS and FPS Under Horizontal Ground Excitation
by Richie Kevin Wouako Wouako, Sandra Céleste Tchato, Euloge Felix Kayo Pokam, Blaise Pascal Gounou Pokam, André Michel Pouth Nkoma, Eliezer Manguelle Dicoum and Philippe Njandjock Nouck
Buildings 2025, 15(9), 1498; https://doi.org/10.3390/buildings15091498 - 28 Apr 2025
Viewed by 340
Abstract
The study of vibration isolation devices has become an emerging area of research in view of the extensive damage to buildings caused by earthquakes. The ability to effectively isolate seismic vibrations and maintain the stability of a building is thus addressed in this [...] Read more.
The study of vibration isolation devices has become an emerging area of research in view of the extensive damage to buildings caused by earthquakes. The ability to effectively isolate seismic vibrations and maintain the stability of a building is thus addressed in this paper, which evaluates the effect of horizontal ground excitation on the response of a structure isolated by a coupled isolation system consisting of a non-linear damper (QZS) and a friction pendulum system (FPS). A single-degree-of-freedom system was used to model structures whose bases are subjected to seismic excitation in order to assess the effectiveness of the QZS–FPS coupling in reducing the structural response. The results obtained revealed significant improvements in structural performance when the QZS–FPS system uses a damper of optimum stiffness. A 30% reduction in displacement was recorded compared with QZS alone for two signals, one harmonic and the other stochastic. The response of the QZS–FPS system with soft stiffness to a harmonic pulse reveals amplitudes reaching around eight times those of the pulse at low frequencies and approaching zero at high frequencies. In comparison, the rigid QZS–FPS coupling has amplitudes 0.9 and 3.5 times higher than those of the harmonic signal. Thus, the resonance amplitudes observed for the QZS–FPS system are lower than those reported in other studies. This analysis highlights the performance differences between the two types of stiffness in the face of harmonic pulses, underlining the importance of the choice of stiffness in vibration management applications. The stochastic results show that on both hard and soft soils, the new QZS–FPS system causes structures to vibrate horizontally with maximum amplitudes of the order of 0.003 m and 0.007 m respectively. So, QZS–FPS coupling can be more effective than all other isolators for horizontal ground excitation. In addition, the study demonstrated that the QZS–FPS combination can offer better control of building vibration in terms of horizontal displacements. Full article
(This article belongs to the Section Building Structures)
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18 pages, 3773 KiB  
Article
A Novel Hybrid Metaheuristic MPA-PSO to Optimize the Properties of Viscous Dampers
by Elmira Shemshaki, Mohammad Hasan Haddad, Mohammadreza Mashayekhi, Seyyed Meisam Aghajanzadeh, Ali Majdi and Ehsan Noroozinejad Farsangi
Buildings 2025, 15(8), 1330; https://doi.org/10.3390/buildings15081330 - 17 Apr 2025
Viewed by 410
Abstract
Nowadays, it is very important to reduce structural vibrations and control seismic reactions against earthquakes. Nonlinear viscous dampers are known as one of the effective tools for absorbing and dissipating earthquake energy to reduce structural responses. The characteristics of nonlinear viscous dampers, including [...] Read more.
Nowadays, it is very important to reduce structural vibrations and control seismic reactions against earthquakes. Nonlinear viscous dampers are known as one of the effective tools for absorbing and dissipating earthquake energy to reduce structural responses. The characteristics of nonlinear viscous dampers, including the damping coefficient, axial stiffness, and velocity exponent, play a crucial role in their performance. In this research, the optimization of nonlinear viscous damper characteristics to minimize the peak absolute displacement of the roof in three- and five-story reinforced concrete flexural frames under the El Centro earthquake record has been investigated. Structural modeling and dynamic analyses are performed using OpenSees 3.5.0 software, and damper parameter optimization is performed through a new combination of two marine predator algorithms (MPA) and particle swarm optimization (PSO). Furthermore, the performance of the new algorithm is compared with each of these methods separately to evaluate the efficiency improvement for displacement reduction. The results show that the hybrid algorithm has demonstrated significant performance improvement compared to the independent methods in identifying optimal values. Specifically, in the three-story frame, the roof displacement using the MPA-PSO method was 0.77026, which is lower than 0.77140 with the PSO method. Additionally, the damping coefficient in this method decreased to 14.22824 kN·s/mm, which is a significant reduction compared to 19.32417 kN·s/mm in the PSO method. Furthermore, in the more complex five-story frame, the two comparison methods were unable to reach the optimal solution, while the proposed method successfully found an optimal solution. These results validate the performance and advantages of the proposed hybrid algorithm. Full article
(This article belongs to the Section Building Structures)
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29 pages, 7936 KiB  
Article
Dynamic Response of a 15 MW Jacket-Supported Offshore Wind Turbine Excited by Different Loadings
by Renqiang Xi, Lijie Yu, Xiaowei Meng and Wanli Yu
Energies 2025, 18(7), 1738; https://doi.org/10.3390/en18071738 - 31 Mar 2025
Viewed by 820
Abstract
This study investigates the dynamic behavior of a jacket-supported offshore wind turbine (JOWT) by developing its substructure and controller tailored for the IEA 15 MW reference wind turbine. A fully coupled numerical model integrating the turbine, jacket, and pile is established to analyze [...] Read more.
This study investigates the dynamic behavior of a jacket-supported offshore wind turbine (JOWT) by developing its substructure and controller tailored for the IEA 15 MW reference wind turbine. A fully coupled numerical model integrating the turbine, jacket, and pile is established to analyze the natural frequencies and dynamic responses of the system under wind–wave–current loading and seismic excitations. Validation studies confirm that the proposed 15 MW JOWT configuration complies with international standards regarding natural frequency constraints, bearing capacity requirements, and serviceability limit state criteria. Notably, the fixed-base assumption leads to overestimations of natural frequencies by 32.4% and 13.9% in the fore-aft third- and fourth-order modes, respectively, highlighting the necessity of soil–structure interaction (SSI) modeling. During both operational and extreme wind–wave conditions, structural responses are governed by first-mode vibrations, with the pile-head axial forces constituting the primary resistance against jacket overturning moments. In contrast, seismic excitations conversely trigger significantly higher-mode activation in the support structure, where SSI effects substantially influence response magnitudes. Comparative analysis demonstrates that neglecting SSI underestimates peak seismic responses under the BCR (Bonds Corner Record of 1979 Imperial Valley Earthquake) ground motion by 29% (nacelle acceleration), 21% (yaw-bearing bending moment), 42% (yaw-bearing shear force), and 17% (tower-base bending moment). Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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26 pages, 6886 KiB  
Article
Numerical and Experimental Seismic Characterization of Byblos Site in Lebanon
by Rita Abou Jaoude, Nisrine Makhoul, Alexandrine Gesret and Jean-Alain Fleurisson
Geosciences 2025, 15(3), 82; https://doi.org/10.3390/geosciences15030082 - 23 Feb 2025
Cited by 1 | Viewed by 789
Abstract
Geological and topographic site effects lead to variations in the spatial distribution of ground motion during large earthquakes. Despite the impact of such phenomena, they remain poorly understood. There is a lack of joint studies of numerical predictions and experimental observations on the [...] Read more.
Geological and topographic site effects lead to variations in the spatial distribution of ground motion during large earthquakes. Despite the impact of such phenomena, they remain poorly understood. There is a lack of joint studies of numerical predictions and experimental observations on the geomorphological site effects. Therefore, a comparison between well-constrained models and experimental field observations is needed. Byblos is a seismic region in Lebanon surrounded by faults that historically generated destructive earthquakes. Its geological and geomorphological settings are interestingly characterized by fractured rocks and anthropic deposits altering seismic ground motions. Field surveys in Byblos gathered ambient vibration recordings and surface waves. It identified multiple resonant frequency peaks, suggesting impedance contrasts and lateral variations in subsurface stiffness, using Horizontal-to-Vertical Spectral Ratio (HVSR) and directivity. It also revealed soft, shallow layers with low velocities, indicating potential resonance during earthquakes, using Multichannel Analysis of Surface Waves (MASW) and 2D seismic arrays. Thus, our study on Byblos is a first step for seismic microzoning of the area that evaluated its heterogeneous subsoil, soft surface layers, and anthropic deposits. Finally, combining geophysical data and field measurements with a numerical model allowed a better understanding of Byblos seismic hazards and enhanced its resilience and sustainability. Full article
(This article belongs to the Section Natural Hazards)
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14 pages, 4173 KiB  
Article
Ground Motion Recording-Based Validation of Capacity Curves for High-Rise Reinforced Concrete Structures in Romania Constructed Before 1977
by Florin Pavel
Buildings 2025, 15(4), 549; https://doi.org/10.3390/buildings15040549 - 11 Feb 2025
Viewed by 508
Abstract
Capacity curves are essential in the evaluation of seismic fragility of structures and especially in seismic risk assessments. The most widely used approach for evaluating capacity curves is based on static nonlinear analyses performed in dedicated software. However, a validation of such curves [...] Read more.
Capacity curves are essential in the evaluation of seismic fragility of structures and especially in seismic risk assessments. The most widely used approach for evaluating capacity curves is based on static nonlinear analyses performed in dedicated software. However, a validation of such curves is necessary considering the uncertainties associated with the analyses. Overall, 18% of the population of Romania that lives in reinforced concrete buildings inhabits high-rise structures. In Bucharest, the percentage of people living in the same category of structures is more than 40%. A large part of these structures was built before the Vrancea 1977 earthquake. In this context, this paper presents a review of existing capacity curves for this category of high-rise reinforced concrete structures in Romania. Next, an analysis of relevant ground motions recorded on buildings during various Vrancea intermediate-depth earthquakes (1986 and 1990) is performed. In addition, results from various ambient vibration measurements are also used for a more thorough understanding of the dynamic characteristics of the buildings and of their stiffness. A comparison between the analytical capacity curves and the data from ground motion recordings is presented, highlighting significant differences, especially for reinforced concrete frame structures. Finally, updated capacity curves for high-rise residential structures constructed before 1977 are proposed by combining the analytical results with the earthquake data. Full article
(This article belongs to the Section Building Structures)
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29 pages, 9768 KiB  
Article
Modeling, Design, and Laboratory Testing of a Passive Friction Seismic Metamaterial Base Isolator (PFSMBI)
by Shayan Khosravi and Mohsen Amjadian
Materials 2025, 18(2), 363; https://doi.org/10.3390/ma18020363 - 15 Jan 2025
Cited by 1 | Viewed by 1126
Abstract
This paper focuses on the theoretical and analytical modeling of a novel seismic isolator termed the Passive Friction Mechanical Metamaterial Seismic Isolator (PFSMBI) system, which is designed for seismic hazard mitigation in multi-story buildings. The PFSMBI system consists of a lattice structure composed [...] Read more.
This paper focuses on the theoretical and analytical modeling of a novel seismic isolator termed the Passive Friction Mechanical Metamaterial Seismic Isolator (PFSMBI) system, which is designed for seismic hazard mitigation in multi-story buildings. The PFSMBI system consists of a lattice structure composed of a series of identical small cells interconnected by layers made of viscoelastic materials. The main function of the lattice is to shift the fundamental natural frequency of the building away from the dominant frequency of earthquake excitations by creating low-frequency bandgaps (FBGs) below 20 Hz. In this configuration, each unit cell contains an inner resonator that slides over a friction surface while it is tuned to vibrate at the fundamental natural frequency of the building. This resonance enhances the energy dissipation capacity of the PFSMBI system. After deriving the governing equations for four selected lattice configurations (i.e., Cases 1–4), a parametric study is performed to optimize the PFSMBI system for a wide range of harmonic ground motion frequencies. In this study, we examine how key parameters, such as the mass ratios of the cells and resonators, tuning frequency ratios, the number of cells, and the coefficient of friction, affect the system’s performance. The PFSMBI system is then incorporated into the dynamic model of a six-story base-isolated building to evaluate its effectiveness in reducing the floor acceleration and inter-story drift under actual earthquake ground motion records. This dynamic model is used to investigate the effect of stick–slip motion (SSM) on the energy dissipation performance of a PFSMBI system by employing the LuGre friction model. The numerical results show that the optimized PFSMBI system, through its lattice structure and frictional resonators, effectively reduces floor acceleration and inter-story drift by leveraging FBGs and frictional energy dissipation, particularly when SSM effects are properly accounted for. Finally, a small-scale prototype of the PFSMBI system with two cells is developed to verify the effect of SSM. This experimental validation highlights that neglecting SSM can lead to an overestimation of the energy dissipation performance of PFSMBI systems. Full article
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13 pages, 7496 KiB  
Article
The Dynamic Response of an Arch Dam During a Recorded Low-Intensity Earthquake
by Jorge P. Gomes and José V. Lemos
Appl. Sci. 2025, 15(1), 35; https://doi.org/10.3390/app15010035 - 24 Dec 2024
Viewed by 786
Abstract
The dynamic behavior of a concrete arch dam, the Baixo Sabor dam, built in Portugal, is investigated. A numerical model was developed to represent the dam, foundation, and reservoir system. This model was calibrated and validated through comparison with experimental data from forced [...] Read more.
The dynamic behavior of a concrete arch dam, the Baixo Sabor dam, built in Portugal, is investigated. A numerical model was developed to represent the dam, foundation, and reservoir system. This model was calibrated and validated through comparison with experimental data from forced vibration tests and ambient vibration monitoring. Recently, a low-intensity earthquake occurred in the region and the dam response was recorded by a seismic monitoring system. The previously calibrated numerical model was used to analyze the dynamic response of the dam under this seismic input, employing a dynamic boundary formulation that takes into account the wave propagation in the rock mass, preventing wave reflections. The results obtained show generally good agreement with the experimental measurements at the dam crest and abutments. The analysis methodology and the main issues involved in the modelling of arch dams under seismic action are discussed. Full article
(This article belongs to the Section Civil Engineering)
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15 pages, 6487 KiB  
Article
Seismic Response Analysis of Hydraulic Tunnels Under the Combined Effects of Fault Dislocation and Non-Uniform Seismic Excitation
by Hao Liu, Wenyu Yan, Yingbo Chen, Jingyi Feng and Dexin Li
Water 2024, 16(21), 3060; https://doi.org/10.3390/w16213060 - 25 Oct 2024
Viewed by 1237
Abstract
Hydraulic tunnels are prone to pass through faults and high-intensity earthquake areas, which will cause serious damage under fault dislocation and earthquake action. Fault dislocation and seismic excitation are often considered separately in previous studies. For tectonic earthquakes with higher frequency in seismic [...] Read more.
Hydraulic tunnels are prone to pass through faults and high-intensity earthquake areas, which will cause serious damage under fault dislocation and earthquake action. Fault dislocation and seismic excitation are often considered separately in previous studies. For tectonic earthquakes with higher frequency in seismic phenomena, fault dislocation and ground motion are often associated, and fault dislocation is usually the cause of earthquake occurrence, so it is limiting to consider the two separately. Moreover, strong earthquake records show that there will be significant differences in the mainland vibration within 50 m. The uniform ground motion inputs in previous studies are not suitable for long hydraulic tunnels. This paper begins with the simulation of non-uniform stochastic seismic excitations that consider spatial correlation. Based on stochastic vibration theory, multiple multi-point acceleration time-history curves that can reflect traveling wave effects, coherence effects, attenuation effects, and non-stationary characteristics are synthesized. Furthermore, a fault velocity function is introduced to account for the velocity effect of fault dislocation. Finally, numerical analyses of the response patterns of the tunnel lining under four different conditions are conducted based on an actual engineering project. The results indicate the following: (a) the maximum lining response values occur under the combined effects of fault dislocation and non-uniform seismic excitation, indicating its importance in the seismic resistance of the tunnel. (b) Compared to uniform seismic excitation, the peak displacement of the tunnel under non-uniform seismic excitation increases by up to 6.42%, and the peak maximum principal stress increases by up to 28%. Additionally, longer tunnels exhibit a noticeable delay effect in axial deformation during an earthquake. (c) Under non-uniform seismic excitation, the larger the fault dislocation magnitude, the greater the peak displacement and peak maximum principal stress at the monitoring points of the lining. The simulation results show that the extreme response values primarily occur at the crown and haunches of the tunnel, which require special attention. The research can provide valuable references for the seismic design of cross-fault tunnels. Full article
(This article belongs to the Special Issue Water Engineering Safety and Management)
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25 pages, 21311 KiB  
Article
Experimental Study on Seismic Performance Evaluation of a Multi-Story Steel Building Model with Rolling-Type Seismic Base Isolation
by Hakan Öztürk, Erkan Çelebi and Cemalettin Kaya
Buildings 2024, 14(10), 3268; https://doi.org/10.3390/buildings14103268 - 15 Oct 2024
Cited by 1 | Viewed by 1595
Abstract
Critical structures such as hospitals, high-precision manufacturing facilities, telecommunications centers, and fire stations, especially, need to maintain their functionality even during severe earthquakes. In this sense, seismic isolation technology serves as a vital design method for preserving their functionality. Seismic isolators, also known [...] Read more.
Critical structures such as hospitals, high-precision manufacturing facilities, telecommunications centers, and fire stations, especially, need to maintain their functionality even during severe earthquakes. In this sense, seismic isolation technology serves as a vital design method for preserving their functionality. Seismic isolators, also known as earthquake isolation systems, are used to reduce the effects of earthquakes on buildings by isolating them from the ground they are located on. By ensuring that less acceleration and force demand is transmitted to the superstructure, both the building and the equipment and the devices in the building are prevented from being damaged by earthquakes. This experimental study aims to conduct vibration tests on a small-scale multi-story steel-building model equipped with a specially designed rolling-type seismic base isolation system. The relationship between the test model and the prototype was achieved by frequency simulation. The tests will be performed on a shake table under six different earthquake accelerations to examine the model’s dynamic behavior. The primary goal is to evaluate the isolation performance of the rolling-type seismic base isolator under seismic loads, with a focus on recording the vibrations at the top of the test building. It has been observed that the isolator placed at the base of the building significantly reduced the peak acceleration and displacement values of the floor motion. Under the most severe earthquake record applied to the shake table, the acceleration at the top of the building with the isolator was found to be reduced by approximately 50%, compared to the non-isolated case. Full article
(This article belongs to the Section Building Structures)
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16 pages, 9117 KiB  
Article
Methodology and Monitoring of the Strengthening and Upgrading of a Four-Story Building with an Open Ground Floor in a Seismic Region
by Iakov Iskhakov, Sharon Yehuda and Yuri Ribakov
Appl. Sci. 2024, 14(17), 7581; https://doi.org/10.3390/app14177581 - 27 Aug 2024
Cited by 3 | Viewed by 1308
Abstract
Many buildings around the world fail to meet current earthquake resistance requirements and have significant potential to be a risk to human life and property. Therefore, a seismic upgrade of such buildings is quite necessary. Over the past decades, hundreds of buildings have [...] Read more.
Many buildings around the world fail to meet current earthquake resistance requirements and have significant potential to be a risk to human life and property. Therefore, a seismic upgrade of such buildings is quite necessary. Over the past decades, hundreds of buildings have been strengthened and upgraded to improve their seismic resistance, and thousands more are planned for years to come. In Israel, this was followed by National Outline Plan No. 38, which provides a basis for retrofitting and adding new areas to existing buildings. It should be noted that adding new floors to existing buildings increases seismic forces. Moreover, structure material properties change over a building’s lifetime, which should be also considered for strengthening. The proposed research investigates and validates the existing practice for strengthening and upgrading buildings in seismic regions and suggests ways of improving their efficiency. Experiments and numerical analysis were performed on a real existing residential building that requires strengthening and upgrading. A corresponding methodology was proposed for monitoring the strengthening and upgrading processes, including selecting measurement devices and their real use. Using sensors with the highest sensitivity enabled measurements of micro-vibrations and investigations of the recorded signal to obtain the building’s natural vibration frequencies. Experimental measurements allowed us to distinguish different frequencies of the building at all strengthening and upgrading stages. The measured dynamic parameters of the building allowed a more accurate calculation of seismic forces for all of these stages and consequently made the design more effective. Therefore, we recommended monitoring buildings in each stage of seismic strengthening and upgrading. Full article
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23 pages, 11691 KiB  
Article
Cost-Effective Data Acquisition Systems for Advanced Structural Health Monitoring
by Kamer Özdemir and Ahu Kömeç Mutlu
Sensors 2024, 24(13), 4269; https://doi.org/10.3390/s24134269 - 30 Jun 2024
Cited by 6 | Viewed by 5304
Abstract
With the growing demand for infrastructure and transportation facilities, the need for advanced structural health monitoring (SHM) systems is critical. This study introduces two innovative, cost-effective, standalone, and open-source data acquisition devices designed to enhance SHM through the latest sensing technologies. The first [...] Read more.
With the growing demand for infrastructure and transportation facilities, the need for advanced structural health monitoring (SHM) systems is critical. This study introduces two innovative, cost-effective, standalone, and open-source data acquisition devices designed to enhance SHM through the latest sensing technologies. The first device, termed CEDAS_acc, integrates the ADXL355 MEMS accelerometer with a RaspberryPi mini-computer, ideal for measuring strong ground motions and assessing structural modal properties during forced vibration tests and structural monitoring of mid-rise buildings. The second device, CEDAS_geo, incorporates the SM24 geophone sensor with a Raspberry Pi, designed for weak ground motion measurements, making it suitable for seismograph networks, seismological research, and early warning systems. Both devices function as acceleration/velocity Data Acquisition Systems (DAS) and standalone data loggers, featuring hardware components such as a single-board mini-computer, sensors, Analog-to-Digital Converters (ADCs), and micro-SD cards housed in protective casings. The CEDAS_acc includes a triaxial MEMS accelerometer with three ADCs, while the CEDAS_geo uses horizontal and vertical geophone elements with an ADC board. To validate these devices, rigorous tests were conducted. Offset Test, conducted by placing the sensor on a leveled flat surface in six orientations, demonstrating the accelerometer’s ability to provide accurate measurements using gravity as a reference; Frequency Response Test, performed at the Gebze Technical University Earthquake and Structure Laboratory (GTU-ESL), comparing the devices’ responses to the GURALP-5TDE reference sensor, with CEDAS_acc evaluated on a shaking table and CEDAS_geo’s performance assessed using ambient vibration records; and Noise Test, executed in a low-noise rural area to determine the intrinsic noise of CEDAS_geo, showing its capability to capture vibrations lower than ambient noise levels. Further field tests were conducted on a 10-story reinforced concrete building in Gaziantep, Turkey, instrumented with 8 CEDAS_acc and 1 CEDAS_geo devices. The building’s response to a magnitude 3.2 earthquake and ambient vibrations was analyzed, comparing results to the GURALP-5TDE reference sensors and demonstrating the devices’ accuracy in capturing peak accelerations and modal frequencies with minimal deviations. The study also introduced the Record Analyzer (RECANA) web application for managing data analysis on CEDAS devices, supporting various data formats, and providing tools for filtering, calibrating, and exporting data. This comprehensive study presents valuable, practical solutions for SHM, enhancing accessibility, reliability, and efficiency in structural and seismic monitoring applications and offering robust alternatives to traditional, costlier systems. Full article
(This article belongs to the Special Issue Structural Health Monitoring Based on Sensing Technology)
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22 pages, 8620 KiB  
Article
Design and Validation of a Stratified Shear Model Box for Seismic Response of a Sand-Blowing Reclamation Site
by Jiaguang Li, Yi Wei, Tenglong Liang, Yuanfang Yan, Ying Gao and Xiaoyan Lu
Buildings 2024, 14(5), 1405; https://doi.org/10.3390/buildings14051405 - 14 May 2024
Viewed by 999
Abstract
The global increase in building collapses and damage on soft-soil sites due to distant significant earthquakes poses similar challenges for sand-blowing reclamation (SBR) sites on soft-soil layers. This study was initiated to capture the vibration characteristics of the SBR sites and to provide [...] Read more.
The global increase in building collapses and damage on soft-soil sites due to distant significant earthquakes poses similar challenges for sand-blowing reclamation (SBR) sites on soft-soil layers. This study was initiated to capture the vibration characteristics of the SBR sites and to provide fresh insights into their seismic responses. Initially, considering the heterogeneity and layered structure of soil at SBR sites, we developed a novel stratified shearing model box. This model box enables the simulation of the complex characteristics of soil layers at SBR sites under laboratory conditions, representing a significant innovation in this field. Subsequently, an innovative jack loading system was developed to apply active vertical pressure on the soil layer model, accelerating soil consolidation. Furthermore, a new data collection and analysis system was devised to monitor and record acceleration, pore water pressure, and displacement in real time during the experiments. To verify the model box’s accuracy and innovation, and to examine the seismic response of SBR sites under varying consolidation pressures, four vibration tests were conducted across different pressure gradients to analyze the model’s predominant period evolution due to consolidation pressures. The experimental results demonstrate that the model box accurately simulates the propagation of one-dimensional shear waves in soil layers under various consolidation pressures, with notable repeatability and reliability. Our experiments demonstrated that increasing consolidation pressure results in higher shear wave speeds in both sand and soft-soil layers, and shifts the site’s predominant period towards shorter durations. Concurrently, we established the relationship between the site’s predominant period and the input waves. This study opens new paths for further research into the dynamic response properties of SBR sites under diverse conditions through shaking-table tests. Full article
(This article belongs to the Special Issue Construction in Urban Underground Space)
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23 pages, 2091 KiB  
Article
Design and Performance Assessment of Base Isolated Structures Supplemented with Vibration Control Systems
by Evangelos Sapountzakis, Georgios Florakis and Konstantinos Kapasakalis
Buildings 2024, 14(4), 955; https://doi.org/10.3390/buildings14040955 - 30 Mar 2024
Cited by 8 | Viewed by 1537
Abstract
This paper investigates the implementation of supplemental vibration control systems (VCS) in base isolated (BI) structures, to improve their dynamic performance. More specifically, the aim of the VCS is to reduce the base displacement demand of BI structures, and at the same time [...] Read more.
This paper investigates the implementation of supplemental vibration control systems (VCS) in base isolated (BI) structures, to improve their dynamic performance. More specifically, the aim of the VCS is to reduce the base displacement demand of BI structures, and at the same time mitigate the superstructure seismic responses. The purpose of the examined VCS is dual, and for this reason a multi-objective optimization methodology is formulated for the design of the VCS. The examined vibration absorbers include modifications of the KDamper concept. The KDamper is an extension of the traditional Tuned Mass Damper (TMD), and introduces a negative stiffness (NS) element to the additional oscillating mass of the TMD. The generated NS force is exactly in phase with the inertia force of the added mass, thus, artificially amplifying it. This way, lighter configurations are possible with an enhanced damping behavior. These VCS are designed based on engineering criteria and manufacturing constraints, while the excitation input used in the multi-objective optimization procedure is selected from a dataset of artificial accelerograms, designed to be spectrum-compatible with the EC8 design acceleration response spectrum. The effectiveness of the examined VCS is also assess with real near-fault earthquake records, and a comparison is performed with TMD-based VCS having 50 times larger additional masses. The numerical results demonstrate the superiority of the KDamper-based VCS in improving the dynamic behavior of BI structures over other mass-related systems (TMD). Full article
(This article belongs to the Special Issue Sustainable Preservation of Buildings and Infrastructure)
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