Prediction Of Train Induced Vibrations Research Articles

An efficient three-dimensional dynamic stiffness-based model for predicting subway train-induced building vibrations

The prediction of train-induced vibration in buildings constructed above the subway is a challenging problem due to its sophisticated system and time-consuming calculation. This paper proposes an efficient three-dimensional (3D) dynamic stiffness-based model (DSM) to predict subway train-induced building vibrations. The DSM has the capability to analytically explore the axial, bending, and torsional vibrations of columns and beams, as well as the flexural and in-plane vibrations of floors and walls induced by the moving train, which few studies have focused on before, and has high computational efficiency compared to the traditional finite element method (FEM). In the DSM, the dynamic stiffness matrices of floors, walls, columns and beams are formulated by the stiffness theory firstly. Then, the global dynamic stiffness matrix of the building is determined following an assembly procedure and the vibration responses of the building can be calculated by the dynamic stiffness equation in the frequency domain. Further, the calculation accuracy and efficiency of the DSM are validated by comparison with a 3D finite element model. Finally, the DSM is used to predict the train-induced vibrations of a building constructed at a subway station based on a subway train-slab track coupled dynamics model. Results show that the building vibrations induced by the moving train are significant in both vertical and horizontal directions and the steel-spring floating-slab track can effectively suppress the train-induced building vibrations.

A hybrid methodology for predicting train-induced vibration on sensitive equipment in far-field buildings

The prediction of train-induced vibration on far-field buildings is a challenging issue in the transportation environment communities. In this work, a hybrid prediction method is put forward utilizing the idea of substructure analysis, which can high-effectively calculate the train-induced vibration under different operation conditions. Based on vehicle-track coupled dynamics theory, wavenumber finite element theory (2.5D FEM) and Green’s function method, this method could comprehensively analyze vibration characteristics of the source, propagation path and sensitive target/vibration receiver by appropriately considering the boundary conditions between each part. The proposed model possesses the advantages of 2.5D FEM in calculation efficiency and could consider the dynamic interaction between vehicle and track system more elaborately. In addition, the vibration response under different operation conditions can be high-efficiently obtained by updating the track supporting forces without repeatedly solving the Green’s functions of the system. On this basis, this work predicts the vibration impact of subway train operation on the sensitive equipment in a far-field large-scale building, and uses the generic vibration criteria for sensitive equipment to evaluate the vibration responses. Further, to mitigate the impact of train-induced vibration, floating slab track is adopted to achieve the vibration attenuation in the concerned frequency. Results show that the train-induced vibration on the monolithic bed track exceeds the limit specified in the standard in some frequency bands. The use of floating slab track can effectively reduce the vibration response of the building and ensure the routine use of sensitive equipment.

Numerical modeling of train-induced vibration of nearby multi-story building: A case study

In recent years, ground vibration has become a popular research topic due to the growing construction close to vibration sources and the attentiveness of people about living conditions. Thus, vibrations caused by the passage of the train near buildings play an important role. In prediction of train-induced vibrations, many experimental and theoretical methods have been proposed. In order to study the vibration near the railway at Qaemshahr, a 2D finite element analysis employed for modeling of the train movement and its effect on the adjacent building. The validation of the numerical model was done by the high-speed train running measurements. The results show that the vibration level decreases by increasing the track centerline to building distance and decreasing train speed. The frequency of vibration up to 12 Hz was present in the incident wave field and the dominating part of the frequency content was between 2.5 and 5.5 Hz. The building foundation bending moment variations caused by train-induced vibrations was negligible. The track centerline to building edge distance of 18 m was seemed to be an acceptable value to reduce the annoyance and environmental effects caused by train-induced vibrations.

Measurement and prediction of train-induced vibrations in a full-scale building

Buildings located close to transportation corridors experience structure-borne sound and vibration due to passing traffic which can be disruptive to operation of sensitive equipment in manufacturing, and medical facilities. Structure-borne sound and vibrations, when high may also be annoying to human occupants in residential, office, and commercial buildings. Hence, there is a growing need for cost effective sound and vibration predictions to evaluate the need for mitigation.The research focuses on in-situ testing of a full-scale building for verification of a previously developed impedance-based methodology and to create a prediction model to study ground-borne vibrations in the test building. A mitigation methodology was also examined using the verified prediction model.Impedance modeling involves the propagation of axial waves through columns combined with the impedance of the intermediate floor slabs. The vibration transmission in the building was characterized and predicted using a single column model with attached floors.Train-induced floor vibrations in an existing four-story building in Boston were measured and compared with predictions of the impedance model. The impedance model predictions closely matched with the measured floor responses.A previously suggested mitigation method was investigated analytically using the impedance model. A thickened floor referred as the “blocking floor” was used on the lower elevation of the building and the reduction in vibration at the upper floors of the building was compared for various thicknesses of the blocking floor, to study its efficiency. The blocking floor has high impedance and reflects a major portion of the vibration transmitting in the columns preventing it from reaching the upper floors. The blocking floor was found to mitigate the transmission of ground-borne vibrations to upper floors.