Innovative composite overpasses on the Romanian A1 motorway - Economical Bridge Solutions based on Innovative Composite Dowels and Integrated Abutments - page 141

Over the last four years, VFT- and VFT-WIB bridges solutions have been applied in
Romania. The following structures can be mentioned: the bridge over the Mânărău channel
on the national road DN79A or the road bridge over Bistriţa river, country Vâlcea, with a
total length of 63,30 m which is under construction, two VFT ® overpasses on the A1 motor-
way, section Orăştie - Sibiu lot 1, one for the county road DJ705 and the second one for the
national road DN7.
From the first introduction of the prefabricated composite beams VFT ® (Verbundfer-
tigteil - Träger) in the year 1998, through a sustained and systematic research activity several
steps forward were made regarding the development of efficient and innovative solutions
for composite bridges by creating an efficient connection between the steel and the concrete
structure [1]. The research ideas were a success and proved a very good quality and efficiency
of the constructive parts (the main girders) which are entirely made in the workshop. The ef-
ficiency consists in the elimination of the classical Nelson type connectors and implicitly of
the upper flange of the steel section, and creating a new type of composite dowels by cutting
the steel web according to a predetermined contour (“Fig. 2”).

The idea and the new VFT ® generation VFT ® classic solution

Figure 2: VFT ® solution for composite bridges [1]

2. Technical details of the applied solutions

In case of the new VFT ® the connection between steel and concrete is made through com-
posite dowels and the upper steel flange is needed no more. If the elimination of the upper
flanges of the steel girders and the studs are considered, namely material consumption and
welding workmanship, the efficiency of the designed solution can be observed. The solution
represents an inspired alternative to the classical concrete bridges - particularly to those with
pre-stressed girders on the cross section. Using the high degree of prefabrication, the VFT ®
girders reduce the possibility of unexpected situations on site and offer execution simplic-
ity and by default obtaining lower costs. The reduced weight of the prefabricated composite
beams offers advantages both in the transportation as well as in the manipulation efforts and
contributes to the success of modern composite bridges.
Both passages have only one span and are oblique (approximately 70°), integral struc-
tures and they use four steel-concrete composite beams approximately 39 m long (“Fig. 3”).