Applied Mechanics and Materials Vol. 617

Abstract: Natural frequencies and natural modes represent the basic dynamic characteristics of all dynamic systems. They define the dynamic individuality of dynamic system. It is useful to know approximate relations giving the results with adequate accuracy. The analysis of plates in contact with elastic foundation is the part of structural dynamic which demands hard numerical solutions. The submitted paper presents approximate relations enabling to carry out the assessment of natural frequencies of the slabs on elastic foundation at variable stiffness with satisfactory accuracy.

Abstract: The operation of railway tracks is historically confirmed that the classic structure of the railway superstructure is capable to ensure operational capability of standard railway tracks for a relatively long period of time (railways tracks to speed of 160 km.h^-1). Such a railway track and its track is considered the railway track with a classic structure of the railway superstructure, where track removal is stored in the ballast. In the case of high operating and axle load, increasing track speed and requirements for safety of operation, which are associated with high requirements on the track geometry, it appears that such structure has its operational (in terms of guaranteeing the long-term safety and reliability of the railway track) and economic (in terms of the cost of maintenance of railway track) limits. "Floating" placement of the track removal during each passage of a rail vehicle, or train leads to the growth of dynamic horizontal and vertical forces that cause gradual degradation of track geometry, what subsequently leads to restless journey of moving rail vehicles. Elimination of imperfections in track geometry - the quality of the railway track - forces the operators to remove such imperfections of railway track in time and financially consuming maintenance work in certain periods. However, it is sufficient if only the weakest element of classic railway superstructure is replaced in the railway, and it is the track ballast using other more appropriate component representing no elastic and plastic behaviour. The structure is such replacement, in which the track removal is concreted (monolithic structure) or stored on a concrete or asphalt bearing layer (layered structure), namely structural design, which is referred to as unconventional railway superstructure. The structure of railway superstructure is characterized by cross sleepers used in a modified shape or they are not part of it at all. Currently, thus conceived railway track is referred to as a slab track (hereinafter referred to as the "ST"), which requires flexibility of the railway superstructure for the system of the wheel/rail secured using elastic elements disposed between the rail and the sleeper and/or under the sleeper. In general, the structure of ST has been currently applied mainly to high-speed track and the tracks that have high operational load, where the cost of maintaining the track with the classic structure of the railway superstructure strongly grows. At the same time, however, this structure also promotes in the upgraded sections of the standard tracks (track speed to 160 km.h^-1), especially in track sections conducted in tunnels, as there are located the required properties of the ballast that do not demonstrate subsidence. The subgrade without a drop also offers for application of the ST structure bridges, and therefore, the application of this structure is also possible in these track sections.

Abstract: ŠKODA VÝZKUM s.r.o. (now Výzkumný a zkušební ústav Plzeň s.r.o.) cooperated on the development of the NEOPLAN DMA low-floor articulated trolleybus indented for the City of Boston. Multibody models and finite element models of the trolleybus were utilized in the stage of the vehicle design. The effect of using the rear section stabilizer on driving properties of the trolleybus was investigated utilizing the multibody simulations among others.

Abstract: Ground-supported cylindrical tanks are used to store a variety of liquids. The fluid was develops a hydrodynamic pressures on walls and bottom of the tank during earthquake. This paper provides dynamic time-history response of concrete open top cylindrical liquid storage tank considering fluid-structure interaction due to earthquake. Numerical model of cylindrical tank was performed by application of the Finite Element Method (FEM) utilizing software ADINA. Arbitrary-Lagrangian-Eulerian (ALE) formulation was used for the problem analysis. Two way Fluid-Structure Interaction (FSI) techniques were used for the simulation of the interaction between the structure and the fluid at the common boundary

Abstract: Proposed an engineering method for calculating the fine quay walls of the seismic action. At the initial stage is the stress-strain state of the walls of the static load taking into account the redistribution of lateral earth pressure. In the presence of an earthquake is determined by seismic lateral earth pressure on the wall from the effects of inertia forces, added mass of water pressure and dynamic load from various forms of oscillations of the wall. Seismic load fluctuations wall defined by dynamic spectral method as a result of decomposition of seismic vibrations in a series of major modes of vibration. The results of the proposed calculation realized in the program «SCAD», and have been compared with «Plaxis - 2D» results.

Abstract: This paper presents the nonlinear dynamic analysis of the reinforced concrete building of nuclear power plant to the aircraft impact. The dynamic load is defined in time on the base of the simulation of the airplane impact considering real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

Abstract: Safety and reliability of the communication steel bridge of the nuclear power plant under extreme loads is considered in this paper. The extreme load from the wind and the earthquake is defined for the probability of exceedance 10^-4 per year on the base of the last results from the investigation in Slovakia. The deterministic and the probabilistic assessments to verify the safety and reliability of the structure are presented. The uncertainties of the input data and the calibration of the load factors are discussed. The advantages and disadvantages of the probabilistic analysis are discussed. The advantages of the utilization the LHS method to analyze the safety and reliability of the structures is presented.

Abstract: The paper determines the parameters of the explosion wave excited by a terrorist charge and assumption of the building structure of a railway station based on dynamic analysis. Certain simplified methods according to various publications, according to our own experimental results and according to 3D computations based on detailed calculation modelling of the interior of the room are compared to determine the explosive effects. Equivalent static analysis was applied to the dynamic response of the structural elements of the selected room. The damage caused to these structural elements is weighted on the basis of the angle of failure of the central axis / surface, and on the basis of the limit stress state of these structures.

Abstract: The paper deals with the analysis of steel beams subjected to blast load approximated as a one degree system of freedom (SDOF). It requires knowing the parameters of blast pressure wave, its effect on structure and the tools for the solution of dynamic analysis. The blast wave is estimated with linear decay and exponential decay using positive and negative phase. The results of SDOF model are compared with the corresponding experimental accelerations and strain time-histories. There is a described dynamic analysis for such structure.

Abstract: Fibre-reinforced composite materials are becoming important in many areas of technological application. In addition to the static load, such structures may be stressed with short-term dynamic loads or even dynamic impact loads during their lifespan. Dynamic effects can be significant especially for thin-walled shell structures and barrier constructions. Impact loading of construction components produces a complex process, where both the characteristics of the design itself and the material parameters influence the resultant behavior. It is clear that reinforced concrete with fibers has a positive impact on increasing the resistance to impact loads. Results of impact load tests carried out on drop-weight test machine are presented in this paper. The results are supplemented by compression strength test.