bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic response of floors induced by a single walking pedestrian: deterministic and probabilistic approaches
Authors: Bayat Elyas , Tubino Federica 
Published: June 2024

Abstract
Current design standards evaluate floor vibration performance by analyzing a single walking individual as a multi-harmonic fixed load applied to the anti-nodes of the floor mode shapes. These guidelines do not consider the impact of varying walking paths on the dynamic response of floors. Moreover, because pedestrian walking forces are inherently stochastic, the deterministic methods employed by current standards can yield unreliable estimations of vibration response. The present paper aims to investigate the dynamic response of simply supported rectangular floors under a single walking pedestrian. At first, a deterministic loading model is assumed; then a probabilistic approach is adopted taking into account the stochastic nature of pedestrian walking force. From the deterministic standpoint, the present study reports an exact closed-form solution to calculate the dynamic response of floors subjected to a pedestrian walking load moving along a generic walking path. Then, an approximated closed-form solution is proposed to calculate the vibration response of floors for the critical walking path which provides the maximum dynamic response. Finally, a probabilistic approach is incorporated to address the variability in both walking load and walking path.
Vibration serviceability assessment of complex-shaped CLT floor
Authors: Milojević M , Racic V , Marjanović M , Nefovska-Danilović M 
Published: June 2024

Abstract
Cross-laminated timber (CLT) floors are typically an assembly of prefabricated panels connected together on the site. CLT offers a wide range of configuration possibilities, as it can be easily pre-cut into various shapes and sizes, making it suitable for use in different architectural design requirements. However, available CLT design guidelines do not apply to complex-shaped CLT floors, i.e. unconventional geometry of floor plans including concave polygons, arches and openings. This paper presents a numerical vibration analysis of such a floor with openings, which represents a standard floor structure for residential and commercial buildings. Influence of panel orientation and inter-panel connections on modal properties and vibration response induced by a single pedestrian walking is analysed and discussed.
Experimental analysis of cross-laminated timber floors
Authors: Nefovska-Danilović M , Racic V , Milojević M , Mišković Z , Savatović S 
Published: June 2024

Abstract
Cross-laminated timber (CLT) floors have gained in popularity due to their outstanding strength, aesthetic appeal, good fire resistance, and high level of prefabrication. However, due to their high stiffness-to-weight ratio, CLT floors are highly susceptible to pedestrian-induced vibrations. In design practice, vibration serviceability is usually assessed by assuming a floor as a set of CLT panels with no inter-panel connections, which leads to overestimation of the vibration response. In this paper, an experimental dynamic testing was carried out to identify modal properties and pedestrian-induced response of two CLT floors with different number of panels in a floor assembly. Influence of the inter-panel connections on the floor modal properties and pedestrian-induced vibration response is particularly studied and discussed.
Floor vibrations from data acquisition with android phones
Authors: Martinelli L , Foti F , Perotti F , Cucchi M 
Published: June 2024

Abstract
Android mobile devices are provided with sensors that allow to monitor several aspects in terms of motion and position of the device; these sensors are hardware-based physical components built into the device, operated by software and mobile apps, providing us with data about motion, temperature, position, and environment in general. Correlation analyses on vibration data recorded on structures are at the base of many methods that allow to extract important modal information from the recorded data. This type of data acquisition demands a high level of time accuracy in order the correlation analyses to be successful. It follows that, whenever data is recorded by different mobile devices, some sort of synchronization between them is required to allow for the necessary precision in time of the recordings. This paper presents the results obtained with a recent solution in which vibration data is picked up with multiple Android mobile phones equipped with accelerometers, and is then transmitted to a server over a wireless connection to be analysed in time on the base of a synchronization procedure. The subject of this study are the recordings of the floor vibrations of a recently constructed building. These are compared with the recordings coming from professional grade acceleration sensors. The capabilities of the proposed recoding technique are discussed on the base of the precision in recovering the mode shapes of a flexible floor from the acceleration records, and also at the light of the relative ease with which Android mobile phones are becoming more available, capable, and less expensive.
Seismic assessment of masonry structures by means of code-based selected records
Authors: Caicedo Daniel , Hussaini Sayed Mohammad Sajad , Karimzadeh Shaghayegh , Bernardo Vasco , Lourenço Paulo B 
Published: June 2024

Abstract
Through the centuries, earthquakes represent one of the main causes of damage and loss of cultural heritage, monumental buildings, and historic centres, affecting the development of many countries worldwide. These kinds of constructions are usually constituted by structural masonry and have shown evidence of good behaviour under vertical static loads, however, given the mechanical properties of this heterogeneous material, such as the high specific mass, low tensile/shear strength, and reduced ductility, makes its use unsuitable in seismic prone areas. This paper conducts a comprehensive study regarding the seismic assessment of an existing masonry structure, using various sets of ground motions selected and fitted to the target elastic response spectrum according to the Eurocode 8 provisions. A comparison between the fitted response spectrum in the period range of 0.2T1-2T1 and in the full period domains is performed.
Measured hospital building vibrations induced by air conditioning systems and elevators
Authors: Rinaldi C , Talebi A , D’Alessio M , Potenza F , Gattulli V 
Published: June 2024

Abstract
A recent large campaign of vibration measurements has been conducted on a hospital building in Italy to perform an operational modal analysis of the structure utilized for model updating. Subsequently, the updated model has been used to carry out a vulnerability analysis of the hospital structural system. The building is composed of 41 structural subsystems separated by technical joints. At the same time, several subsystems are differently interconnected, especially through a roof sustained by large-span wooden beams. Long acceleration time histories have been measured by wireless sensors located at the top level of the building in two days of testing. During the tests conducted in operational conditions, in different locations of the building air conditioning systems and elevators were functioning and they were affecting the measures in the high-frequency content. This work aims to investigate the structural identification of the complex structure, the effectiveness of technical joints, and the influence of the wooden roof connection on the dynamic structural behavior. In pursuing these goals, the main challenge is considering the influence of air conditioning and elevator systems on the natural frequency identification of the structure. Therefore, based on the location of the sensors, the similarities in the geometry, and the vicinity of the sensors to the mechanical equipment, all the sensors have been classified into different groups to observe the dynamic response. Furthermore, an Artificial Neural Network (ANN), trained on numerical model results, is applied to experimental data to establish a relation between increasing prediction error and the influence of the air conditioning system and elevator frequencies.
Dynamics of beams travelled by equally spaced forces via transfer matrix approach
Authors: Migliaccio G. , Ferretti M. , Di Nino S. , Luongo A. 
Published: June 2024

Abstract
This work addresses the dynamic behavior of slender elastic structures travelled by a train of equally spaced transverse forces. Assuming the structures are representable via an Euler-Bernoulli beam, the velocity of the train of forces is constant, and the distance between adjacent forces is equal to an integer submultiple of the beam length, the problem is solved analytically. The analytical solution is based on a linear map, which transforms the system state (positions and velocities of the beam points) at the time instant at which one of the travelling forces leaves the beam from one of its ends, to the system state at the time instant at which the subsequent travelling force in the train leaves the beam from the same end. The reiteration of the linear map provides the time response of the beam. The proposed solution enables the analytical study of the dynamic behavior of the structure and highlights the presence of critical velocities at which divergence phenomena by response accretion may occur. Comparisons with the results of numerical methods confirm the accuracy of the analytical solution.
Train-track-circular tunnel spatially coupled dynamics model and coupling effects of dynamic track-tunnel interactions
Authors: Yang Jianjin , Li Qiuyi , Zhu Shengyang , Zhu Bin , Zhai Wanming 
Published: June 2024

Abstract
The train-induced environmental vibration is an important issue for the rail transport. The study on tunnel vibrations plays an important role in the prediction and evaluation of environmental vibration induced by underground train. A three-dimensional (3D) time-domain train-track-tunnel-soil coupled dynamics model is proposed in this study for the underground circular tunnel commonly used in subway. In the model, the tunnel lining and surrounding grouting area are modelled as a cylindrical dual-layer thin shell supported by cylindrical viscoelastic layer which is used to describe the influences of soil. Subsequently, the partial differential equations of the shell are transformed into ordinary differential ones by using semi-analytic modelling method. Then, the model of tunnel lining and grouting area is coupled with the train-track spatially coupling dynamics model through the track-tunnel dynamic interactions, forming the 3D train-track-tunnel coupled dynamics model. The accuracy and reliability of the proposed model are verified by the field test results. Finally, the model is employed to study the influence of coupled solving of train-track subsystem and tunnel subsystem. Results show that the proposed model can achieve real-time dynamics simulation of the train-track-tunnel spatially coupled system on a desktop computer. The coupling effect between the train-track subsystem and the tunnel subsystem has an evident impact on the dynamic responses of the train, track, and tunnel subsystems.
A numerical model based on moving mesh FE for vehicle bridge interaction
Authors: Greco Fabrizio , Lonetti Paolo , Pascuzzo Arturo , Sansone Giulia 
Published: June 2024

Abstract
The main purpose of the present study is to investigate the effects of damage phenomena on the structural behavior of Reinforced Concrete (RC) bridges and related identification procedures. To this end, an effective FE numerical model able to analyze the structural response, in presence of different damage scenarios, is implemented. Moreover, the influence of moving loads on the damage behavior is also considered by means of the vehicle-bridge interaction (VBI) FE model. The combination of the structural model and the vehicle mechanical system provides an advanced numerical model able to simulate the dynamic interaction between the bridge and the moving vehicle. This problem is managed by using the moving mesh technique. In particular, the formulation “Arbitrary Lagrangian-Eulerian” (ALE) provides an accurate description of the interaction between two systems. ALE approach is based on a fixed-referential system and moving coordinate variables, representing the positions of the computational nodes during the application of the moving loads. Vibrational analyses in terms of damage scenarios are presented to verify how the presence of material discontinuities affects the natural frequencies of the structural system. Moreover, results in terms of dynamic amplification factor for typical design bridge variables, in presence of damage phenomena and moving loads, are also developed. Finally, a discussion on the impact of the proposed results on the dynamic identification procedures is provided.
Nonlinear Earthquake Response Analysis Using Causal Hysteretic Damping and Extended Rayleigh Damping
Authors: Nakamura Naohiro , Nabeshima Kunihiko , Mogi Yoshihiro , Ota Akira 
Published: June 2024

Abstract
In dynamic design, damping considerably influences the response of structures, so it must be set appropriately. Stiffness-proportional damping is generally used as an inherent damping model, but this model tends to overestimate the damping of higher-order modes. Certain models can evaluate the damping of higher-order modes, such as modal damping and Rayleigh damping. One of the authors proposed causal hysteresis damping and extended Rayleigh damping as damping models with a low frequency dependence of the damping ratio. However, although the use of these models for linear analysis has been studied, their application to nonlinear analysis has not been sufficiently studied. Therefore, in this paper, the effect of these inherent damping models on the response characteristics of structures was evaluated to obtain basic data for future research. Specifically, stiffness-proportional damping, Rayleigh damping, modal damping, causal hysteresis damping, and extended Rayleigh damping were studied. Their response characteristics were evaluated and compared. These damping types for nonlinear analysis could be divided into the initial type and the tangential type, depending on how to handle changes in stiffness. These properties were also examined.
Novel three-dimensional non-self-intersecting plots for describing the dynamics of structural systems and their hysteresis
Authors: Gallo Patricio Quintana 
Published: June 2024

Abstract
In earthquake structural dynamics, because the ground acceleration term (external excitation) explicitly depends on the time, the equation of motion of a single-degree-of-freedom (SDOF) system constitutes a nonautonomous 2-dimensional (2D) dynamical system. Thus, the true dimension of the equivalent autonomous dynamical system is three, such that the state is 3-dimensional (3D) and, naturally, so is the phase-space where it should be visualized. The 2D plots of two state variables of a 2D-nonautonomous system, unlike for autonomous counterparts, are self-intersecting. The self-intersecting nature of these 2D plots represents a barrier for a proper visualization of the system’s dynamics and render them unsatisfactory for conducting graphical qualitative evaluations. To cope with such a disadvantage, this paper presents novel 3D non-self-intersecting plots for describing the dynamics of SDOF systems, including those with hysteretic restoring force, as a 3D-autonomous dynamical system. The 3D curves comprise plots incorporating the time as an additional variable as well as others of the type [velocity, restoring force, displacement], which, somehow, resemble Lorentz’s ‘butterfly’ 3D plot obtained for meteorology. The paper uses examples of problems having harmonic and earthquake-induced actions (accelerations) typically encountered in dynamics of structures. In addition, the paper presents 3D curves of the measured force-displacement hysteresis loops of reinforced concrete beam-column joint assemblies tested under quasi-static loading regime. It is shown that the 3D plots allow visualizing relationships and behaviours that cannot be identified using the 2D counterparts. It is thought that the novel 3D curves can be of much use in structural/seismic and mechanical engineering.
On a nonlinear behavior of an aeroelastic system with quartic stiffness
Authors: Machado Raphaela Carvalho , Ribeiro Maurício Aparecido , Varanis Marcus Vinicius Monteiro , Nabarrete Airton , Balthazar José Manoel 
Published: June 2024

Abstract
This research performs a nonlinear analysis of a typical section airfoil limited to two degrees of freedom emphasizing the evaluation of the effects of a quartic structural stiffness on dynamic responses. Analytical studies are presented based on a simulated model. First, the influence of the quartic term of nonlinear structural stiffness in spring moment is evaluated. Then, phase portraits are presented as a function of freestream velocity, and a time domain decomposition of time histories is performed to identify the limit cycle frequency. Additionally, it maps the region of limit cycle oscillations (LCOs). Furthermore, the aim of this work is to characterize the nonlinear aeroelastic response.
An asymptotic approximation of the chattering time for the rocking problem
Authors: Giouvanidis Anastasios I. , Dimitrakopoulos Elias G. , Lourenço Paulo B. 
Published: June 2024

Abstract
The dynamic behaviour of a freestanding block rocking on a rigid base when subjected to a strong ground excitation is a classical problem of nonlinear dynamics that has recently gained considerable momentum. However, when a rocking block is subjected to a low amplitude (i.e. weak) ground motion has drawn little attention due to the belief that it has marginal effect on the response trajectory. Despite its apparent structural simplicity, a rocking block undergoes complex nonlinear and nonsmooth dynamics phenomena under both low and high amplitude ground motions. This study focuses on one of the least investigated nonlinear phenomena of rocking dynamics that might appear during the low amplitude forced oscillations of a block, called chattering. Chattering can be complete or incomplete. Complete chattering occurs when a block undergoes a theoretically infinite sequence of impacts in finite time, that eventually bring the block to the state of persistent (continuous) contact even under a nonzero excitation. On the contrary, incomplete chattering does not bring the block to rest after a theoretically infinite number of impacts. A challenging problem that arises during complete chattering is the accurate estimation of the time needed for the block to reach the state of persistent (continuous) contact, i.e. chattering time. Thus, this paper presents an iterative algorithm that approximates chattering time using asymptotic analysis and perturbation methods.
The seismic responses of the Post-Tensioned frame with Sliding Keys on Inclined Deflecting-cantilevers device (the PT-SKID frame)
Authors: Zhang Y , De Risi R , Alexander N A 
Published: June 2024

Abstract
Recently, a novel Sliding Keys on Inclined Deflecting-cantilevers (SKID) device was proposed for application with Post-Tensioned (PT) frames. The SKID device features a triangular-shaped hysteretic curve, which enables it to provide hysteretic damping with a zero activation threshold. The PT-SKID frame is characterised by a dual-triangular-flag-shaped hysteretic curve with full self-centring capability. The properties of the PT frame and the SKID device have been theoretically investigated and physically demonstrated. In this paper, the hysteretic curve of the PT-SKID frame is discussed first. There are three core parameters for the SKID device: friction coefficient μ, slope angle β, and cantilever bar stiffness k
s. Then, the influence of these parameters on the seismic response of the PT-SKID frames is investigated by numerically testing 560 PT-SKID frames in OpenSees. Three pairs of spectrum-matched ground motions are used in the analysis. The results indicate that SKID devices with a small β and large k
SKID and μ have a better peak drift ratio control. However, larger sections have to be used for the structural components supporting the SKID devices, as a larger base shear is generated.
Uncertainty parameters of the floor response spectrum in a seismically isolated structure
Authors: Lee S J , Kim S Y , Byun Y J , Kim J H 
Published: June 2024

Abstract
To evaluate the earthquake safety of the equipment in structures, it is essential to analyze the Floor Response Spectrum (FRS). FRS has a peak value at a frequency corresponding to the structural vibration mode; however, the frequency and amplitude at the peak can vary because of many uncertain parameters. Several seismic design criteria exist for FRS peak-broadening in fixed-base structures. However, no criteria for constructing a design FRS for seismically isolated structures have been suggested. The FRS of isolated structures may change because of the major uncertainty parameter of the isolator, which is the shear stiffness of the isolator, and several other uncertainty parameters caused by the nonlinear behavior of the isolators. This study evaluated the effects of the initial stiffness of the bilinear curve of isolators and the variation in the effective stiffness based on the input ground motion intensity and intense motion duration. An analysis of a simplified structural model for an isolated base structure confirmed that the FRS at the frequency of the structural mode was amplified and shifted. The uncertainty in the initial stiffness of the isolators was found to significantly affect the shape of the FRS. The variations caused by the intensity and duration of the input ground motion were also evaluated. These results suggest several considerations for generating FRS for seismically isolated structures.
Finite element model updating of a ferry dock bridge
Authors: Siedziako B , Nord T S , Fenerci A 
Published: June 2024

Abstract
An accurate finite element representation of a real structure allows designers to investigate how it will perform over time when exposed to external loading in order to ensure economical de-sign, structural safety, and a more accurate estimation of the remaining useful life of that structure. For structures such as ferry dock bridges that have been little studied in the past, there are many uncertainties related to properly modelling in finite element software. In such cases, a finite element updating technique can shed a light on uncertain parameters. This paper presents results from the finite element model updating of the Rykkjem ferry dock bridge in Norway based on vibration test data with an emphasis on the estimation of vertical stiffness provided by the lifting towers.