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Due to the types of construction (steel, concrete etc.), the type of excitation (caused by wind, rail and traffic etc.) in the measurement of engineering structures' vibration different measurement techniques and different data processing techniques are used. The paper presents the comparison of Classical and Operational Modal Analysis on the basis of engineering structures. The results of vibration's measurements of selected engineering structures with the use of different methods of data processing are presented and discussed in the paper. Dynamic measurements of a structure were performed with the use of a multichannel PULSE system, produced by the Brüel & Kjaer.

Results of examination and analysis of cracks formation in a composite slab floor in an industrial warehouse hall is presented in the paper. During exploitation of the floor, on which lift trucks and presses worked, a lot of deep cracks occurred in the slab. In order to define characteristics of cracks and properties of concrete there were made different NDT examinations. Measurements of vibrations due to work of presses were also realized with aim to evaluate their possible influence on cracks formation. Static, dynamic and strength structural calculations were also made based on the model of continuous, multi-bay plate. They showed that applied slab reinforcement was sufficient and acting loads did not have to cause cracks. After 3D modelling of the building and taking into consideration the flexibility of main steel beams it was gained that in the RC floor slab over supports bending moments could occur nearly three times greater than calculated from the 2D model. Taking into consideration wrong structural model of the building led to over-loading of the floor slab, its cracking and caused a necessity of its strengthening.

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A new methodology of physical and FE modelling and simulation of bridge-track -moving train (BTT) systems has been developed with the use of commercial CAE systems. A methodology is related to composite (steel-concrete) bridges, ballasted tracks and high-speed trains. In the methodology, Altair HyperMesh, LS-DYNA, LS-PrePost and HyperView software was applied. The methodology is based on homogenization of reinforced concrete (RC) platform slab, RAIL_TRACK and RAIL_TRAIN LS-Dyna's modules for simulating the moving train-track interaction, non-linear modelling of rail fastenings and crushed stone ballast, application of cylindrical and revolute constrained joints and discrete springs and dampers for modelling suspensions in rail-vehicles. For experimental validation of numerical modelling and simulation of BTT systems, the KNI 140070 composite viaduct and the EuroCity EC 114 train moving at 160 km/h have been selected. The experimental setup contained Keyence LK-G 157 system (CCD laser displacement sensors), PULSE system (acceleration sensors), and PHANTOM v12 high-speed camera. According to the experiment plan, selected vertical displacements and vertical and horizontal accelerations vs. time were measured. The simulated time-histories of displacements and accelerations have been compared to respective experimental diagrams. The results have proved that the validation is positive.