Cantilevered wooden framework
The self-supporting wooden falsework for erecting arched bridges made of reinforced concrete is a development from the 1960s. The technology goes back to the development of a Graz company based on an idea by the engineer Eusebio Cruciani (Rome). The falsework construction for long-span bridge arches consists of several individual parts; the truss arches made of laminated belts and diagonal bars. Cruciani also had the idea of assembling the self-supporting falsework on site. The finished elements are positioned using a crane . In particular, the production of the reinforced concrete arch in combination with the falsework enables a significant reduction in the dimensions of the scaffolding. Some constructions also make it possible to lower the scaffolding after completion of the reinforced concrete arch for the first half of the bridge and move it horizontally by one lane width in order to then be used again to produce the reinforced concrete arch for the second half of the bridge.
The entire technology has already been invented and further developed several times. The wooden construction is based on the old idea of the French timber designer Emy (1830). Even then, halls with a span of up to 100 m were built with two and three-chord trusses. There were changes in the details: The pressure in the belts was created by bolts and steel clamps when the halls were built. In bridge construction, this task is replaced by round steel shackles with turnbuckles. This device has a double function as a tension diagonal and to compress the plank bundles of the belts.
Several arch bridges with the self-supporting Cruciani falsework were built along the Brenner A13 motorway in the 1960s, later on the Tauern Railway , such as the Falkenstein Bridge or the Pfaffenberg Bridge .
advantages
- economics
- Reusability of wood and fasteners