Applied Mechanics and Materials Vol. 837

Abstract: The computer software used in design work allows the analysis of structures to be conducted in an increasingly detailed way. A great advantage of computer programs is the opportunity to reflect the entire buildings or their significant parts. However, this often leads to calculations being prolonged. When using advanced numerical tools is not possible, the use of simplified models becomes necessary. The paper presents the proposed ways of modelling wide beams connected with flat slabs. As a point of reference for simplified models (shell-shell and shell-beam model), a spatial model consisting of volumetric models was developed.

Abstract: The probabilistic design analyses a plate involving uncertain input parameters. These input parameters (geometry, material properties, boundary conditions, etc.) are defined in the software model. The variations of input parameters are defined as random input variables and are characterized by their distribution type (Gaussian, lognormal, etc.) and by their distribution parameters (mean values, standard deviation, etc.). During a probabilistic analysis, software executes multiple analysis loops to compute the random output parameters as a function of the set of random input variables. The values for the input variables are generated either randomly (using Monte Carlo simulation) or as prescribed samples (using Response Surface Methods). In the conclusion, some results of these probabilistic methods are presented.

Abstract: The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

Abstract: The sport fans behaviour has changed in recent decades, especially on football and ice hockey stadiums in the Czech Republic. Currently the fans more support their sport teams with more intensive cheering like as jumping or swaying. The main results of an experimental analysis that was focused on fans behaviour and simultaneously on the induced vibrations of a selected cantilever grandstand sector during a football match are mentioned in the paper. The actual types of fans cheering, the changes in fans behaviour during the match, relative proportion of active and passive spectators, the features and the levels of grandstand vibrations were investigated in detail.

Abstract: The article deals with the analysis of the problem of the load-bearing capacity of reinforcing bars placed above the columns in slab-column connections of reinforced concrete structures. Failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. The EC2 standard guidelines recommend the use of integrity reinforcement, however, they lack any instructions concerning the amount of necessary reinforcement. The article presents a theoretical calculation model that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar stiffness and considerable deflections. The calculation model is based on the results of experimental investigations. On the basis of a theoretical model it is possible to estimate the tensile force of the bar at which the bars located directly in the support zone are ruptured.

Abstract: The cable-stayed bridge at the inner ring road in Prague in the Czech Republic was put into operation in 1997. The longest bridge span is supported by fourteen cable-stay pairs and next fourteen ones are symmetrically situated on the other side of the pylon. The cable-stays in the ten longest cable-stay pairs are tied together since the bridge construction to prevent vibrations of individual cables caused by wind. The experiment described in the paper was carried out because the large amplitudes of vibrations (about fifteen centimetres) were observed visually on some medium-length cable-stays in April 2015. The experimental analysis was focused on the nine day long continual observation of the selected six cable-stays vibrations during the standard bridge operational state. The analysis of probable causes and the recommended measures to reduce observed large vibrations are mentioned in the paper.

Abstract: The method using Born-Jordan transformation has been developed for the evaluation of response signals obtained by rail fastening analysis. In the paper the laboratory measurements and dynamic parameters analyses of flexible fastening of Vossloh SKL14 type have been descripted. This method can also be used for designing new fastening systems and their parts, for comparison of various rail fastening types and so on.

Abstract: The bearing capacity of a scarf joint depends on the length of the joint and the type of connection. It is possible to use circular bolts or squared dowels. Both connection tools used in the repairs of historic timber structures are made of wood according to the requirements of the heritage authority.

Abstract: This paper presents a practical application of form-finding process of cable-membrane structures. The dynamic relaxation method with kinetic damping is used as the computation method for numerical analysis. A brief description of the construction, a description of the models and the way of solving tasks will be introduced. The correct operation of the implemented algorithm will be compared with a commercial program.

Abstract: The planar frames whose members consist of a laced built-up members are often used in civil engineering practice. For chords of these structures the 1^st order theory internal forces and the assessment by equivalent column method are mostly used. In the equivalent column method the buckling length according to the global buckling mode of the structures should be used. If the distance between neighboring nodes is used as the buckling length of the chord, which is the common case, the second order effects with only the bow imperfections between nodes are taken into account in the equivalent column method. For frames sensitive to buckling in a sway mode the second order effects on structures with initial sway imperfection should be taken into account. Therefore, also in frames with the laced compression columns, where the effects of additional sway deformation cause additional normal forces in the chords, the sway imperfection should be applied and the second order in frame analysis should be performed to check these additive forces. This paper deals with the simplified procedure how to evaluate additive forces due to second order effects on the structure with the global sway imperfection.