Research into filler-beam deck bridges with encased beams of various sections

Abstract

Load-bearing structures of deck railway bridges with encased filler beams have been used for short and middle spans of a maximum of 24 metres. For over a hundred years they have been designed in cases with little headroom. The first bridges were constructed with no interaction between steel beams and concrete floor slabs, the structural steel working as a bearing element and the concrete in the structure as a hardening and filling element. Later, in the second half of the 20 century, more developed bridge designs were introduced where encased steel beams were used acting compositely with a concrete floor slab – the concrete transmitting actions in compression and the steel acting in tension. These structural designs were based on the method of permissible stresses and have been in use up to present. According to [6] it can be assumed that bridges designed employing this methodology meet the requirements stipulated in the current technical standards. Filler-beam deck bridges with encased steel beams are more and more commonly used nowadays, especially in construction and reconstruction of railways. In reconstructions, they are mainly used in replacement of bridges with direct railway bedding that do not comply with relevant standards in terms of the required velocities and operational aspects. Basic rules and requirements set for the design of filler-beam deck bridges are provided in STN EN 1994-2, a European standard that specifies some common structural design and verification rules for sections based either on the plastic theory (providing that cross-sections are classified as Class 1 or 2 according to the abovementioned standard) or on the elastic theory. According to the specified standard, mechanical shear connection need not be provided. th