Modernizace mostu Řečany n. Labem

The bridge structure “Řečany nad Labem” is designed as a continuous steel-concrete girder structure with three spans of 8.9 + 89.0 + 8.9 m, carrying Road III/3227 across the Elbe River. The load-bearing structure consists of steel box girders with a composite reinforced concrete deck made of Corten weathering steel.
The supporting structure is characterized by the variable geometry of the box girders. The cross-section changes in height and shape along the length of the bridge, including changes in the position of the flanges and the orientation of the walls. These elements are neither parallel nor perpendicular throughout their entire extent, which, in combination with the longitudinal curvature and superelevation, leads to the creation of spatial (non-planar) components.
The structural model was developed with an emphasis on the ability to unfold individual sheet metal parts from flat sheets. An analysis of the basic geometry identified areas with multiple curvatures that could not be unfolded directly. These sections were modified by approximation and division into smaller segments to comply with manufacturing tolerances and processing capabilities. The design also respects the constraints imposed by the maximum sheet dimensions and manufacturing capacities.
Part of the preparation of the design documentation involved optimizing the placement of cutouts on the sheet metal sheets (2D nesting) with the aim of reducing material waste. Parametric modeling tools were used for this solution, enabling iterative optimization while taking manufacturing constraints into account.
The variable geometry of the structure places increased demands on the production and design of weld details. Depending on the thickness of the sheet metal and the shapes of the components, not only standard mechanical bending techniques but also thermal forming were used. Welding, particularly for fully penetrated joints, requires consideration of residual stress formation. The geometry of the elements also affects the weld bevel angles, which vary along the joints, and limits accessibility for welding.