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    Fatigue Resistance and Durability of New Mechanical Connections of Currently Developed Temporary Steel Footbridges and Railway Bridges
    (Elsevier, 2015-09-01) Karmazínová, Marcela; Melcher, Jindřich
    On the workplace of paper authors, the experimental studies of the fatigue behaviour and fatigue resistance of several new types of steel mechanical connections have been performed recently. The problems of mechanical connections mentioned above have been solved in the past within the projects of the development of new types of advanced temporary steel bridges and footbridges, with the support of the programme of applied research, development and innovations of the Technology Agency of the Czech Republic. These newly developed connections represent the assembly joints based on the bolts and pins together with plates. Within this investigation, fatigue tests of connections have been performed. The experimental studies have been oriented to the verification of the behaviour of those connections and especially, the fatigue strength, and subsequently the fatigue resistance and durability of the structural detail according to the configuration and structural design.
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    Cast Screws as Shear Anchors for Composite Slabs
    (Elsevier, 2017-07-20) Holomek, Josef; Bajer, Miroslav; Vild, Martin
    Composite slabs consist of trapezoidal steel sheeting and concrete cover. The steel sheeting serves as both, a lost framework and a tension bearing member after hardening of concrete. The longitudinal shear between the sheeting and the concrete must be ensured by a mechanical interlock, for example shear studs or prepressed embossments in the sheeting. The traditional massive shear studs have to be welded to the supporting construction of the slab. Alternatively, thin screws can be drilled through the sheeting and cast into the concrete to ensure the composite action or to strengthen the composite slab in reconstructions locally. The usage of the screws is not limited to the steel supporting frames. This paper describes laboratory tests of the composite slabs with cast screws of various diameters and the effect of the screws on the bending capacity of the slab in combination with prepressed embossments.
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    Kvalita koleje v průběhu času
    (ECON publishing, s.r.o., 2018-01-25) Dušek, Erik
    Článek se zabývá možnostmi zkoumání vývoje kvality koleje v průběhu času. Kvalita koleje se hodnotí podle hodnot jednotlivých geometrických parametrů koleje. Kolej se hodnotí buď úsekově, nebo lokálně. Při lokálním způsobu hodnocení se hledají potenciální problematická místa, zatímco v úsekovém jde o posuzování částí železniční trati, které posléze slouží k plánování údržbových prací. Podrobné zkoumání trendu kvality koleje a následné vyhodnocování získaných dat pomáhá k ekonomickému využívání prostředků na udržování železniční sítě. Součástí článku je i prvotní vyhodnocení dat ze zkušebního úseku.
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    Conditional Stability and Asymptotic Behavior of Solutions of Weakly Delayed Linear Discrete Systems in R^2
    (Hindawi, 2017-06-12) Diblík, Josef; Boháčková, Hana; Šafařík, Jan
    Two-dimensional linear discrete systems $$ x(k+1)=Ax(k)+\sum\limits_{l=1}^{n}B_{l}x_{l}(k-m_{l}),\,\,\,k\ge 0 $$are analyzed, where $m_{1}, m_{2},\dots, m_{n}$ are constant integer delays, $0
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    Test Arrangement of Small-scale Shear Tests of Composite Slabs
    (Elsevier, 2016-10-19) Holomek, Josef; Bajer, Miroslav; Vild, Martin
    Composite slab consists of the layer of concrete above the trapezoidal sheeting. The sheeting serves as a lost formwork as well as a tension bearing member after the hardening of concrete. The interaction between the sheeting and the concrete is necessary for composite action and can be ensured by prepressed embossments in the sheeting. According to nowadays codes, full scale bending tests are required in the design of the new sheeting of this type of composite slabs. An alternative longitudinal shear tests of a small part of the slab have already been derived by many authors. However, the testing arrangement is not unified. The results of the shear tests can be influenced by the magnitude and the way of application of the clamping force, the loading speed, the interface conditions and others. This paper presents a proposal of the testing arrangement and the recommendations for the testing procedure of small-scale shear tests. The recommendations are posted based on the results of several series of performed laboratory tests.