One-dimensional Wave Propagation Research Articles

PREDICTION OF MEGATHRUST IMPACT ON SEISMIC RESPONSE IN SELEBAR DISTRICT OF BENGKULU CITY

Bengkulu City was hit by major earthquakes in 2000 and 2007 with magnitudes of 7.9 Mw and 8.6 Mw. In 2022 BMKG Baai Island, Bengkulu City, said that there is a potential for an earthquake with a maximum magnitude of 8.9. This study was conducted to determine the response of soil layers due to megathrust earthquake wave propagation in Selebar district, Bengkulu City. The study began with field investigations at six points. The seismic response analysis was built based on a one-dimensional wave propagation model with non-linearity. The 2007 Bengkulu-Mentawai earthquake wave with a magnitude of 8.8 Mw was applied as the input wave. PGA, acceleration response spectra, and amplification factors are presented in this study. The resulting PGA ranged from 0.328g - 0.453g. Five points experienced amplification with amplification factors of 1.093 - 1.317. The spectral acceleration has generally exceeded the applicable design spectral acceleration at a period of 0.2 seconds. The spectral accelerations have generally exceeded the applicable seismic design at short periods, with maximum values of 1.27g - 1.64g. So it is necessary to update the seismic design for building planning in Selebar District, Bengkulu City.

Shock wave overpressure distribution behaviour in free-field by reactive filling piercing projectile penetrating multi-layered plates

Abstract The experiment of reactive filling piercing projectile (RFPP) penetrating the multi-layered structural plates is conducted to investigate the impact-induced initiation model and behind-plate deflagration shock wave overpressure mechanism is developed according to the explosion similarity principle and the one-dimensional stress wave propagation theory. The concept of effective deflagration point is proposed to reveal the propagating mechanism of deflagration shock wave. The results demonstrate that at the impact velocity of 688 m/s, the position of initiated reactive filling deflagrated behind the plates range from 0375 to 0.05192m. A significant multi-peak characteristic is presented in the relationship between behind-plate overpressure and time, as a result of the sequential impact behaviour of RFPP impacting the multi-layered plates, with the later overpressure peak exceeding the initial one.

Non-dimensional linear analysis of one-dimensional wave propagation in tensegrity structures

Non-dimensional linear analysis of one-dimensional wave propagation in tensegrity structures

Insight into the dynamic tensile behavior of deep anisotropic shale reservoir after water-based working fluid cooling

Insight into the dynamic tensile behavior of deep anisotropic shale reservoir after water-based working fluid cooling

Sequence Deep Learning for Seismic Ground Response Modeling: 1D-CNN, LSTM, and Transformer Approach

Accurate seismic ground response analysis is crucial for the design and safety of civil infrastructure and establishing effective mitigation measures against seismic risks and hazards. This is a complex process due to the nonlinear soil properties and complicated underground geometries. As a simplified approach, the one-dimensional wave propagation model, which assumes that seismic waves travel vertically through a horizontally layered medium, is widely adopted for its reasonable performance in many practical applications. This study explores the potential of sequence deep learning models, specifically 1D convolutional neural networks (1D-CNNs), long short-term memory (LSTM) networks, and transformers, as an alternative for seismic ground response modeling. Utilizing ground motion data from the Kiban Kyoshin Network (KiK-net), we train these models to predict ground surface acceleration response spectra based on bedrock motions. The performance of the data-driven models is compared with the conventional equivalent-linear analysis model, SHAKE2000. The results demonstrate that the deep learning models outperform the physics-based model across various sites, with the transformer model exhibiting the smallest average prediction error due to its ability to capture long-range dependencies. The 1D-CNN model also shows a promising performance, albeit with occasional higher errors than the other models. All the data-driven models exhibit efficient computation times of less than 0.4 s for estimation. These findings highlight the potential of sequence deep learning approaches for seismic ground response modeling.

Influence of a waveform on the bit–rock impact response considering reflected waves in a drill rod

Influence of a waveform on the bit–rock impact response considering reflected waves in a drill rod

Inspection of Foundation Structures with Pile Integrity Test (PIT) of Steel Tower Building

Pile Integrity Test (PIT) is a tool from Pile Dynamic Inc. (PDI), consisting of a mini-computer, accelerometer, and hammer. Integrity testing on piles using PIT equipment is carried out by analyzing one-dimensional wave propagation provided by hammer blows on the pile head. An accelerometer sensor installed on the pole will read the reflection that occurs during wave propagation on the pole head. The wave propagation speed that occurs in concrete will range from 3,500 m/s to 4,200 m/s. The PIT test results indicate the reduction in impedance in the pole by the BTA value, which compares the theoretical impedance value to the residual impedance. From the results of the Pile Integrity Test carried out at three pile points, it was found that all samples experienced a reduction in impedance around a depth of ± 3.0 meters below the sensor with BTA values of 75%, 78%, and 72% and fell into the damaged category. The reduction in impedance at a depth of 3 meters is most likely part of the connection between piles because one pile point uses 2–3 spun piles, with the length of 1 spun pile being 9 meters. From the results of visual observations, it can be seen that the condition of the existing spun pile and pile cap is still quite good.

Enhanced wave absorption due to local flexibility on wide beams using mass-spring-damper scatterers

It is known that total absorption of flexural waves in a thin beam is possible through the use of monopole-dipole scatterers. In this study, we introduce a pair of identical monopole scatterers for near-total absorption of flexural waves in a thin and wide beam. Despite the two scatterers being both of the monopole type, the resonant modes of the scatterer pair exhibit monopole and dipole properties. By selecting the proper width for the beam, the two resonant modes degenerate, which leads to the total absorption. Although the beam is considerably wide, the frequency range of interest remains below the cut-on frequency of the n = 1 propagating mode, ensuring one-dimensional flexural wave propagation. Further simulations and theoretical analysis revealed that the degeneracy of the monopole and dipole modes results from their interaction with a higher-order localized flexural mode. The simulation results demonstrate absorption exceeding 99%, complemented by experimental data showing approximately 90% absorption.

Design and Validation of a Stratified Shear Model Box for Seismic Response of a Sand-Blowing Reclamation Site

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.

An improved algorithm for Finite Particle Method considering Lagrange-type remainder

An improved algorithm for Finite Particle Method considering Lagrange-type remainder

Hopkinson bar impact force measurement for application to development of an artificial bird

Hopkinson bar impact force measurement for application to development of an artificial bird

Comparative Studies between Frequency Domain Analysis and Time Domain Analysis on Free-Field One-Dimensional Shear Wave Propagation

In Korea, the underground silo structure for low- and intermediate-level radioactive waste disposal facilities has been constructed and operated since 2014. Large-scale earthquakes occurred in 2016 and 2017, respectively, in Gyeongju and Pohang areas near the underground silo structures, and interest in the stability of the underground silo increased significantly. In this paper, one-dimensional free-field analyses have been carried out before the three-dimensional silo dynamic analyses subjected to earthquake loadings. As an additional study, a new form of the finite element equilibrium equation is derived in terms of relative motions, which is essentially the same equation expressed in terms of total motions where the base shear force is applied to the earthquake load. The accuracy of conventional finite element solutions is evaluated by directly comparing them with closed-form solutions by frequency domain analysis such as SHAKE91.

Thermodynamically extended symplectic numerical simulation of viscoelastic, thermal expansion and heat conduction phenomena in solids

AbstractSymplectic numerical schemes for reversible dynamical systems predict the solution reliably over large times as well, and are a good starting point for extension to schemes for simulating irreversible situations like viscoelastic wave propagation and heat conduction coupled via thermal expansion occuring in rocks, plastics, biological samples etc. Dissipation error (artificial nonpreservation of energies and amplitudes) of the numerical solution should be as small as possible since it should not be confused with the real dissipation occurring in the irreversible system. In addition, the other well-known numerical artefact, dispersion error (artificial oscillations emerging at sharp changes), should also be minimal to avoid confusion with the true wavy behavior. The continuum thermodynamical aspects (respect for balances with fluxes, systematic constitutive relationships between intensive quantities and fluxes, the second law of thermodynamics with positive definite entropy production, and the spacetime-based kinematic viewpoint) prove valuable for obtaining such extended schemes and for monitoring the solutions. Generalizing earlier works in this direction, here, we establish and investigate such a numerical scheme for one-dimensional viscoelastic wave propagation in the presence of heat conduction coupled via thermal expansion, demonstrating long-term reliability and the applicability of thermodynamics-based quantities in supervising the quality of the solution.

Experimental Study on the Boundary Reflection Effect of Stress Wave Propagation Based on the Newly Developed Test Apparatus

There is a ubiquitous boundary reflection effect of stress wave propagation in the indoor experimental studies. It is critical to improve the validity of waveform data by optimizing boundary materials to absorb reflection waves. In the present study, a calculation method for the optimal wave impedance of boundary materials was proposed based on the transmission and reflection principle of one‐dimensional stress waves at the interface of different media. By using the calculation method, the optimal wave impedance value of the boundary material was obtained. A one‐dimensional stress wave propagation test apparatus was developed for exploring the improvement effect of absorbing materials on the boundary reflection effect. One‐dimensional stress wave propagation experimental studies in the complete red sandstone samples were carried out by setting various boundary absorbing materials such as pine pad, rubber pad, and steel pad. The results indicated that the experimental test results were consistent with the theoretical calculation results. In the stress wave propagation tests, the optimal wave impedance value of the boundary material was 1.12 × 106 kg/m2·s. When the pine pads were used as boundary absorbing materials, the suppression effect of boundary reflection effects is relatively the best. The present study provides references for analyzing the characteristics and mechanism of stress wave propagation and attenuation.

Track-bridge deformation relation and interaction of long-span railway suspension bridges subject to strike-slip faulting

Track-bridge deformation relation and interaction of long-span railway suspension bridges subject to strike-slip faulting

Appearing shock waves in Arruda – Boyce incompressible rod

The Arruda – Boyce incompressible hyperelastic potentials are used for analyzing one-dimensional acoustic wave propagation in a semi-infinite nonlinearly elastic rod. It has been found that during the propagation of the delta-like pulses, the following phenomena are observed, (i) the shock wave fronts arise; (ii) the pulses spread out due to physical dispersion; (iii) the mechanical energy of the considered system decreases with time, resulting in a decrease of the pulse magnitudes; and, at the same time (iv) thermal energy arises and increases with time, that is caused by formation and propagation of shock wave fronts. The analysis utilizes a combined method consisting of the explicit time integration technique coupled with the finite element method for spatial discretization.

Direct spatio-temporal stress field determination combining full-field deformation measurements and explicit finite element method: Concept verification

Direct spatio-temporal stress field determination combining full-field deformation measurements and explicit finite element method: Concept verification

Longitudinal wave propagation analysis in Entangled metallic wire materials using an improved wave and finite element method

This paper proposes a novel concept and methodology to study longitudinal wave propagation in entangled metallic wire material (EMWM), a porous structural network consisting of spatial helix wires. The numerical model of EMWM is constructed using representative volume elements (RVE) obtained through X-ray tomography and skeletonization of a standard specimen. By increasing the approximate periodic boundary, the improved wave and finite ele-ment method (WFE) is employed to model EMWM as approximately periodic structures, allowing for numerical simulations of wave propagation characteristics. Frequency bands and resonance modes of EMWM are calculated to analyze the characteristics of one-dimensional wave propagation. The numerical results show that EMWM exhibits unique frequency band characteristics compared to typical periodic porous materials. In the frequency range of 15 to n n 35 kHz, the first pass band corresponds to the tensile-compressive motion of the entire specimen, while the higher pass bands correspond to localized vibrations within the spatial wires. Additionally, the frequency bands can be adjusted across a wide range based on the relative density of EMWM specimens. The improved WFE method and obtained numerical data can facilitate the application of EMWM on high frequency vibration isolation.

Computational approach for the acoustic modelling of large aftertreatment devices with multimodal incident sound fields

The influence of multimodal incident sound fields on the acoustic behaviour of large aftertreatment devices incorporating a monolith is modelled and analysed in detail. The analytical mode matching method is applied to the compatibility conditions of the three-dimensional acoustic fields at the device geometric discontinuities, leading to the computation of the complex wave amplitudes in all the subdomains involved and the corresponding device transmission loss. To have a realistic model, three-dimensional propagation must be considered in the inlet/outlet ducts and chambers, while one-dimensional wave propagation has to be assumed along the small capillaries of the aftertreatment device monolith (such catalytic converters and particulate filters); therefore, the monolith can be replaced by a plane wave four-pole transfer matrix from an acoustical point of view. On the other hand, for large aftertreatment device inlet ducts such as those found in heavy-duty and off-road engines, the usual models with plane incident wave excitation are not accurate since the onset of higher order incident modes in the inlet duct is expected for the frequency range of interest. Therefore, a variation of the acoustic attenuation performance is likely to occur depending on these modes, similar to the results previously found in the case of large dissipative silencers. Results are presented for three different multimodal incident sound field hypotheses: equal modal amplitude, equal modal power and equal modal energy density. A relevant influence on the sound attenuation is found for the test problems considered in the current investigation.

Global method for nonlinear seismic analysis of embedded base-isolated nuclear island buildings in layered sites

Global method for nonlinear seismic analysis of embedded base-isolated nuclear island buildings in layered sites