Applied Mechanics and Materials Vol. 617

Abstract: The investigated footbridge across Vltava River in Prague was built in 1984. Almost the entire footbridge structure was overflowed by the extreme flood in August 2002 and the substantial part of the footbridge deck was overflowed afterwards by the great flood in June 2013 again. A significant damage on the footbridge deck was found out by a visual inspection of the load-bearing structure of the footbridge after the second flood. The basic objective of the performed experimental modal analysis was the initial experimental reliability verification of the obviously damaged footbridge structure. The measured natural frequencies and modes were compared with results of the several dynamic tests which were performed regularly during the lifetime of the footbridge. The localization of potential invisible damages was carried out. The recommendations for the range and the arrangement of the static load test, which was performed afterwards for fundamental reliability assessment of a footbridge structure, were made on the basis of the evaluated results of the experimental modal analysis.

Abstract: The presented article is focused on a theoretical dynamic analysis of the footbridge across the Opatovicka street in Prague, which acts as a simply supported beam. The structure was loaded by an ordinary pedestrian traffic, synchronous runners and vandals. The ordinary traffic was simulated by the Monte Carlo method as a stream of moving periodic forces with stochastic parameters. The synchronous runners and vandals were modeled as a combination of biomechanical models of human body, which influenced the structure vibration only passively, and driving forces, which loaded the structure in the contact points between the human body models and the structure. The driving force was the time – dependent function based on decomposition to the Fourier’s Series and periodic triangle function. The obtained theoretical results are compared with experimental data.

Abstract: The composite steel-concrete bridge across the “Slavičí údolí” on the Prague ring exposed to extreme traffic is selected for present traffic flow monitoring. The response of the bridge to the traffic loads is monitored using strain gauges. The record of voltage is converted to the amount of relative deformation, respectively stress in the bottom flange of steel I beam of the bridge. In parallel with the measurements, the computer slab - wall model based on finite element method is developed. The computer model is used for comparison of calculated and measured stresses and deflections in the flanges and to determine the natural frequencies of the examined bridge structure. Calibrated measurements are used for three-year monitoring of the effects of road traffic on bridge facilitating national decision in the National Annex to EN 1991-2.

Abstract: The vehicle-bridge interaction (VBI) is the actual problem of many work places. The mid-span deflection of a bridge versus speed vehicle motion is interested from a practical point of view. Within the solution of the task the numerical methods based on Finite Element Method (FEM) are applied mainly. The task of VBI described in the submitted article is solved by using commercial software ANSYS. The 2-D sprung model of vehicle is modeled as combination of mass, spring and beam elements. The bridge with the mid-range is modeled by simple beam created with beam elements.

Abstract: Pavements represent the transport structures subjected to dynamic effect of moving vehicles. The real transport load is needed for the assessment of pavements. Such data can be obtained by numerical or experimental way. Various computing models can be used for the analysis of concrete pavements. Some possibilities are presented in this contribution.

Abstract: Asphalt pavements are the transport structures subjected to dynamic effect of moving vehicles. Many effects influence the real values of vehicle tire forces. Road unevenness represents the most important factor influencing the magnitudes of tire forces. Such data can be obtained by numerical or experimental way. The paper deals with the numerical simulation of moving load effect on asphalt pavements and with numerical simulation of tire forces in relation to the road unevenness.

Abstract: Fourier transform is an important tool in a number of scientific fields. Its advantages, disadvantages and subtleties have been examined many times by dozens of mathematicians, physicists and engineers. In this contribution we try to summarize important aspects of this transform and discuss variety of its uses in contemporary science with emphasis on demonstrating connections to dynamic interactions in the vehicle-roadway system.

Abstract: Pavements have been damaging during the service life so knowing their current state is valuable and offers important information to choose the right technique to repair the damage caused by vehicles traveling on it. Different kind of diagnostic methods are used for that reason. Many new modern gadgets, which can measure very fast changes of the displacement, have been developed for the last years. Consequently the new modern dynamic diagnostic methods are widely put into service. One of them is FWD Dynatest, which measures displacements on the surface of the pavement while it is loaded by force impulse.

Abstract: Floors which are used for factory building are usually located in an environment where is expected to be used heavy vehicles and also heavy supplies stored on the floor. What means that these structures have to be designed to withstand the action of the forces. For that reason it is useful to do a numerical simulation followed by stress analysis and evaluation of results. The parametric study was done to compare the influence of different thickness and different characteristics of the subgrade on the values of stress in a concrete slab. It was loaded by forklifts and structures used for storage of material and products.