Fexibility of Bridges Built Using the Cantilever Method

The cantilever concreting technology is one of modern methods of constructing the concrete long-span bridges. The fundamental features of this method are saving of materials and of construction costs (especially of scaffolding and of formwork) and first of all a possibility of carrying out the construction of the span in many spots at the same time. The negative feature of these bridges is a large long-term deflection of the bridge, as a result of rheological processes in the concrete and in the pre-tensioning steel. Deflection measurements at the mid-span indicate a visible lowering of the grade line of the bridge span, already after few years of service. The calculated flexibility can be useful in analyses of long-term (rheological) changes in concrete bridge structures. It is a complement to the term bridge stiffness used in the case of momentary (short-term) loads, including dynamic actions.