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The most cost-effective method for reducing vibrations in structures affected by continuous railway traffic is the implementation of an open trench in the ground. However, using deep trenches without lateral support in residential areas is impractical from an engineering standpoint. Furthermore, the screening efficiency of solid wave barriers falls short of expectations. Full-scale field tests to assess the vibration isolation performance of open trenches are either limited or rely on stationary point sources generating periodic surface vibrations. The objective of this study is to investigate both free-field surface ground vibrations and the dynamic response of a specially constructed test building founded on alluvial soil close to high-speed railway traffic, considering both passively isolated and non-isolated conditions. The chosen testing location is Sakarya-Pamukova, a critical area along the Istanbul-Ankara High-Speed Train (HST) line in North-Western Türkiye. To address stability and near-surface groundwater issues, specially designed prefabricated panels with low impedance were placed in the trench. Additionally, the vibration screening performance of infill materials made from recyclable waste materials like wood shavings, Styrofoam, and expanded glass granules was evaluated for the trench-type wave barrier with thin aerated concrete walls. This evaluation considered both structural response and surface wave motions at the test site. In this full-scale experimental study under challenging geotechnical conditions, it has been demonstrated that significant attenuation effects (a reduction of up to 50%) near the high-speed railroad can be achieved at a depth equal to half the wavelength of the excavation. This was accomplished using a thin-walled wave barrier made of low-cost and environmentally friendly lightweight material. By employing various recyclable waste-filling materials, an additional benefit of up to 3 and 5 decibels was observed in vibration mitigation for structural and free field ground vibrations, respectively. • Testing location is a critical area along the Istanbul-Ankara HST line in NW-Türkiye. • In this full-scale experimental study under challenging geotechnical conditions. • Investigation of environmental vibrations caused by HST and reducing using a trench. • Wood shavings, waste Styrofoam and expanded glass granules were used as in-fillings. • The additional benefit of up to 5 decibels was observed with recyclable in-fillings. [ABSTRACT FROM AUTHOR]

In this paper, a simplified methodology of analysis for the seismic response of 3-dimensional irregular high-rise buildings on a rigid footing resting on the surface of a linear elastic half-space is formulated. An efficient method using modal decomposition and carried out in the frequency domain by using the fast Fourier transform to obtain the structural response of torsionally asymmetric buildings, including soil-structure interaction effects, is presented. Applying this algorithm, full advantage is taken of classical normal mode approximation, and the interaction problem is solved easily and effectively within the framework of the Fourier-transformed frequency domain analysis for a fixed-base structure. The matrix formulation of this method produces accurate approximation with less computational effort, in spite of using the frequency dependent impedance functions. [ABSTRACT FROM AUTHOR]

The aim of this study is to consider the effects of the variation of shear modulus ratio (G/G0) and damping ratio (ξ) of soil, obtained by a linear iterative method based on the design spectra of seismic codes, the soil environment in terms of uncertainties in shear modulus using Monte Carlo simulations and the foundation damping (ξf) of flexible base for analyses of the Soil-Structure Interaction (SSI) problems. A squat structure with circular shallow foundation resting on a soil layer over a homogeneous half-space is studied by using cone model and considering seismic zone effect on structural response. Firstly, after showing the effects of the correction of G and ξ on impedance functions and the responses of soil-foundation-structure system, a study is carried out to compare these effects to those of the modelling of uncertainties in shear modulus as random variations. Secondly, a comparative analysis on design response spectra and base shear forces was carried out for four seismic codes (Algerian Seismic Rules RPA99-2003, Eurocode 8–2004, International Building Code IBC-2015 and Indian Code IS-1893-2002) considering the three cases of SSI: SSI effects (initial G and ξ), nonlinear SSI (corrected G and ξ) and stochastic SSI (random G with COV = 20%) compared to the fixed base case. Results show that the correction of G and ξ, according to the equivalent nonlinear method in all the cases, leads to a remarkable decrease in peak responses but show a huge amount of reduction in the second study for IBC-2015 and IS-1893-2002 codes compared to the other codes. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of high-speed train (HST)-induced environmental vibrations using simplified computational models and validates the test results in full-scale field conditions. Experimental investigations and in-situ measurements were performed at the Istanbul-Ankara high-speed railway section to examine the effect of ground vibrations from HSTs on the surrounding residential lands. In this study, ground-borne free-field surface motion at different distances from the railway track was realized using accelerometers. The experimental results of vertical and horizontal ground vibration accelerations induced by HSTs with a velocity of 250 km/h were analyzed. In the first part of the study, a two-dimensional (2D) numerical model based on finite element method (FEM) was used to investigate ground vibrations and validate the experimental results. To minimize artificial reflections and dissipate vibrational energy at the boundaries, the lateral extension of an infinite domain was modeled with viscous absorbing boundaries. A dynamic analysis of the proposed railway-soil coupled model was performed in the time domain under plain-strain conditions using Plaxis 2D, a commercial FEM software. For the verification, the experimental results were compared with those obtained from the numerical analysis. The simplified computational model validated by the test results may help researchers determine further investigation strategies to develop cost-effective mitigation measures for structures with sensitive devices near the railway track and significantly contribute to understanding complex wave propagation problems. In the second part of the study, train-induced environmental ground vibrations were analyzed for different types of soil conditions using a 2D FE model. Computational analyses were performed with four types of soil: soft, medium, dense, and rock, based on the Turkish Earthquake Code. The HST was used as a dynamic source to observe the differences in vibration generation and wave transmission in different types of soil. The HST load on the slab track was simulated to study the effect of operational loads on ground-borne vibrations. Based on the dynamic analysis results, the response of the free-field motion was investigated to obtain the relative acceleration time histories for different points of soil. According to the results, the peak acceleration values of train-induced vibrations at soft, medium, and dense soil sites increased dramatically when compared to the rock site. Vibration measurement data collected from parametric experiments with a simple numerical model for various soil characteristics can be particularly useful when planning residential and industrial facilities at new locations near railroads, to avoid the adverse effects of environmental vibrations caused by HSTs. [ABSTRACT FROM AUTHOR]