River Luznice Bridge, Czech Republic
River Luznice Bridge is located just below the castle in the small town of Bechyne, about 100km from Prague. A new bridge was required to replace the existing steel structure, dating from 1885, which was in poor condition. The attractive and historic sire merited a slender and aesthetically pleasing design for the new bridge, which would integrate into the sensitive environment. Our team in Prague carried out the conceptual and detailed designs, and then supervised construction of this project.

The structural form is a tied 'network' arch, with a steel arch, pre-stressed concrete deck acting as tie, and multiple inclined hangars of stainless steel, 40mm diameter. The span of the bridge is 41m, the rise of the arch is 6m, and with a maximum deck thickness of only 500mm a light and slender appearance is achieved. The network of inclined hangars improves the distribution of local loading and hence reduces bending in the steel arhces concrete deck, helping to achieve the light appearance. The hangars are stressed by the self-weight of the deck and are designed to remain in tension for all loadings. A three dimensional, time dependant analysis was required to calculate long-term behaviour of the structure and buckling effects.

The function of the bridge is to provide access for limited service traffic and pedestrians to this historic area. It is therfore designed to carry one traffic line 3.6m wide and sidewalks on both sides and the overall width of the superstructure is 7.9m. The bridge deck was erected on scaffolding. After assembly of the steel arches, the hangers were tightened, the deck pre-stressed and the scaffolding removed. In order to control stresses, great care was needed in the adjustment of the hanger tensions.