Pavel Ryjáček

Rotational Stiffness of Connections in a Historical Steel Railway Bridge

Traditionally, bridges were solved with steel trusses designed under certain assumptions such as the members being loaded only with axial forces. This assumption is only true if the connections allow the rotation between elements, which in reality is not the case. There are always certain forces transmitted depending on the stiffness of the connection. The following work is intended to determine the rotational stiffness in the connections of a historical steel railway bridge. Different configurations of connections are modeled using component based finite element method (CBFEM) to obtain the real value of the stiffness in the joints. As a result of this analysis, a linear correlation between the value of the rotational stiffness and the number of rivets in the connections is observed. Similarly, there is a linear correlation with the stiffness of the element that is connected in the joint. These results can help to provide an estimate of the rotational stiffness to be considered in a more realistic approach for the assessment of historical railway bridges.

UHPC Railing Panels for a Bridge Renovation in Sázava Municipality

UHPC (ultra high performance concrete) is used mainly within bridge engineering, due to the demand for subtle but strong material, with high durability against aggressive environment. During the last two years, a series of thin-walled railing panels were made in premises of Skanska a.s. company. They were used for a footbridge in Čeperka village, and this year also for a renovation of a bridge SZ-001 in Sázava municipality. The renovation of a bridge, manufacturing of the railing panels, development of its shape and results of conducted test will be presented.

Thermal and load rate-dependent interaction between embedded rail system and bridge

Recent developments in the technology of a modern embedded rail system grant many new possibilities for improving the railway infrastructure. An embedded rail system significantly reduces noise and the dynamical impact affecting both the infrastructure and the rolling stock itself. An embedded rail system may be used for constructing any type of railway infrastructure including high-speed railways. Its attributes are also suitable for modernization of the current steel railway bridges or constructing new structures, where slender bridge decks are required. However, in a railway track equipped with an embedded rail system, stress increments rise due to its restricted expansion movement. This effect is naturally higher when the embedded rail system is placed on a bridge, because of their different deformation possibilities. For a wider use of embedded rail system, examining the interaction behavior between the embedded rail system and the substructure is a matter of essential importance. Furthermore, the nonlinear character of embedded rail system polymer-based components needs to be considered when examining their interaction behavior. Therefore, this paper aims at investigating the nonlinear coupling functions of an embedded rail system under the effects of temperature and load rate. For this purpose, a comprehensive analysis consisting of laboratory experiments, material tests of the embedded rail system components and subsequent numerical validation was performed. Results are concluded in the paper.

Steel bridge in interaction with modern slab track fastening systems under various vertical load levels

In modern slab tracks the continuously welded rail (CWR) is coupled through the fastening system with the substructure. The resulting restriction of expansion movement causes significant rail stress increments, which in the case of extreme loading may cause rail failures. These interaction phenomenon effects are naturally higher on a bridge due to different deformation capabilities of the bridge and the CWR. The presented contribution aims at investigating the state of the art European direct fastening system that is suitable for application on steel bridges. Analysis involves experimental determination of its nonlinear longitudinal interaction parameters under various vertical loads and numerical validation. During experimental procedures a two and a half meter long laboratory sample equipped with four nodes of the Vossloh DFF 300 was tested. There have been checked both DFF 300 modifications using the skl 15 tension clamps and the low resistance skl B15 tension clamps. The effects of clamping force lowering on the interaction parameters have also been investigated. Results are discussed in the paper.