Measurements and predictions of railway-induced vibrations are becoming a necessity in today’s society where land scarcity causes buildings to be put close to railway traffic. The short distances mean an increased risk of the indoor vibration and noise disturbances experienced by residents. In short, the scope of the project is to investigate the transmission loss and vibration level decrease across various junction geometries. The junctions are modelled in both the Finite Element Method (FEM) and the Dynamic Stiffness Method (DSM). Resonances are avoided when possible by using semi-infinite building components. A two-dimensional model that included Timoshenko beams was set up by Wijkmark [1] and solved using the variational formulation of the DSM by Finnveden [2]. The model is efficient and user-friendly but there is no easy way to adjust the junction geometry since the depths of the walls and the floor slabs are the same. From that study, the current topic was formulated. The results presented in this paper indicate that both the Euler-Bernoulli DS model and the three-dimensional FE model have good potential in describing the vibration transmission across the different junction geometries. The two modelling types show more similar results in the analyses of the bending wave attenuation than in the analyses of the quasilongitudinal wave attenuation. One of the probable causes is that the set length of the Perfectly Matched Layers (PML) is not sufficient at such low frequencies. Larger PMLs require bigger geometries that lead to an increase of the computational time. The other proposed reason is the fact that bending waves are created above the asymmetrical junction when the lower beam is excited by a vertical harmonic force. The flexural displacements are neglected in those cases. The results however, were good enough to be satisfactory. Three junction models were investigated and the attenuation is the highest for both wave types in the case with a beam pair attached to the “middle” of an infinite plate. The attenuation is the second highest across the edge of a semi-infinite plate and the lowest across a junction corner of a semi-infinite plate. As part of the suggested future work, the wave transmission between beam and plate needs to be investigated when Timoshenko beams are included in the DS model. In the Euler-Bernoulli beam theory the cross-section remains perpendicular to the beam axis, which is different to the behaviour of solid elements in FEM.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-10-20T18:30:20Z No. of bitstreams: 2 Dissertação - Ana Flávia Paulino de Carvalho - 2016.pdf: 2131091 bytes, checksum: 15ddf737ba58887ff8135af85c0c08d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-10-21T19:25:11Z (GMT) No. of bitstreams: 2 Dissertação - Ana Flávia Paulino de Carvalho - 2016.pdf: 2131091 bytes, checksum: 15ddf737ba58887ff8135af85c0c08d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-21T19:25:11Z (GMT). No. of bitstreams: 2 Dissertação - Ana Flávia Paulino de Carvalho - 2016.pdf: 2131091 bytes, checksum: 15ddf737ba58887ff8135af85c0c08d0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-06-17 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The expansion of the railway network together with the urbanization process resulted in the train induced vibrations analysis. In this work was developed a parametric analysis of ground vibration induced by railway traffic from the representation of the train through a point load, normal to the ground, moving with constant velocity. The wheel load is elastically distributed on the railway track composed by rails, sleepers and ballast, generating the resulting load on the ground. The soil is formulated as a homogeneous, elastic, isotropic and linear solid material, and their displacements are calculated by the use of triple Fourier transform, assuming that the velocity of the train traffic is less than the Rayleigh waves. The methodology of this study is based on developing a computational code using the numerical tool MATLAB. After the validation of this program, the influences of the vibrations induced by rail traffic are analyzed parametrically considering variation in the type and train speed, the characteristics of the railway track, the soil properties and the distance between the observation point and the railroad. The results show the strong influence of several parameters of the problem in the displacement and the instantaneous velocity of ground vibration, especially when the train speed approaches to the speed of Rayleigh waves in the soil. The vibration values obtained are then compared with acceptable levels of current regulations according to the type and human use of buildings which are close to the railway. / A expansão da malha ferroviária aliada ao processo de urbanização acarretaram na necessidade de análise do impacto da propagação da vibração no solo induzida pelo tráfego de trens. Neste trabalho é desenvolvida uma análise paramétrica da vibração do solo induzida pelo tráfego ferroviário a partir da representação do trem através de uma carga pontual normal ao solo movendo-se com velocidade constante. Esta carga de roda é distribuída elasticamente sobre a pista ferroviária composta pelos trilhos, dormentes e lastro, gerando o carregamento resultante no solo. O solo é formulado como um sólido homogêneo, elástico, isotrópico e linear e os seus deslocamentos são calculados através do uso da transformada tripla de Fourier, assumindo que a velocidade de tráfego do trem é inferior à velocidade das ondas de Rayleigh no solo considerado. A metodologia deste trabalho se baseia no desenvolvimento de um programa computacional com a utilização da ferramenta numérica MATLAB. Após a validação deste programa, as influências das vibrações induzidas pelo tráfego ferroviário são analisadas parametricamente a partir da variação do tipo e da velocidade do trem, das características da pista ferroviária, das propriedades do solo e da distância entre o ponto de observação e a ferrovia. Os resultados obtidos apresentam a forte influência dos diversos parâmetros do problema no deslocamento e na velocidade instantânea da vibração do solo, principalmente quando a velocidade do trem se aproxima à velocidade das ondas de Rayleigh no solo considerado. Os valores de vibração encontrados são então comparados com os níveis aceitáveis estabelecidos nas normas vigentes de acordo com o tipo e uso humano da construção que se encontra próxima à ferrovia.

Higher speeds and higher capacity will cause the Swedish rail network to be exposed to disturbing dynamic effects. Higher speeds cause higher vertical acceleration levels of the bridge deck. In this thesis, a numerical analysis of a three span end-frame bridge subjected to train induced vibrations is performed. The aim is to identify which structural components and boundary conditions that affect the dynamic behavior of the bridge. Furthermore, the influence of soil structure interaction (SSI) will be investigated as it may have contribution to the stiffness and damping of the structural system.  In order to capture the dynamic response of the bridge, an analysis in the frequency domain was preformed where frequency response functions (FRF) and acceleration envelopes were obtained. For this purpose, a detailed FE-model in 3D was created. Three different cases were studied, model subjected to ballast, model subjected to soil and model subjected to both ballast and soil in coherence. A high speed load model (HSLM) was used to create simulation of train passages at different speeds and applied to all cases so that the bridge deck accelerations could be studied. A simplified 2D-model with impedance functions representing the soil-structure interaction was created to validate the results from the detailed 3D-model and for practical design purposes.  The result of this numerical analysis showed that the vertical accelerations were within acceptable levels of the maximum allowed limits given in governing publications. Considering the surrounding soil, the results revealed an increase of the dynamic response in the midspan at resonant frequency. However, it was identified that this behavior is not explained by the influence of soil structure interaction but rather the change in boundary conditions of the end-shields. The same dynamic behavior was identified for the simplified 2D-model, with a slight underestimation of the vertical accelerations at resonance.