The architects Lengfeld & Wilisch and engineers Bollinger + Grohmann have completed a new “skylink” bridge between the “the square“ building at the Frankfurt Airport and a 300m-distant carpark. On this bridge a cable car will transport pedestrians from and to the carpark. The bridge is above the street which is the main access road to terminal 1 of the Frankfurt Airport and furthermore it is visible from a four-lane road passing by the ICE tracks and the Autobahn A3. Due to this prominent location a construction with a very high aesthetic quality had to be found.
To meet these demands a trussed steel bridge was designed with diagonals placed by a computer algorithm. The diagonals were placed in a set of structures randomly and the structures were calculated. Structures with bigger deflections were sorted out and diagonals which had no loads where taken out or were replaced by the evolutionary algorithm. This way a structure was created which meets the demands of the statics but still looks randomly created. Since the bridge is visible from above and below the diagonals underneath and above are meeting the diagonals at the sides. These diagonals are placed different Layers to avoid complex nodes where the diagonals are crossing at the sides. The diagonals at the sides which meet diagonals at the top are placed at the outside and the ones meeting diagonals underneath are placed at the inside.
Due to fatigue loading the nodes where the diagonals are connected to the chords had to be designed carefully. The typical nodes and the special nods where calculated with Finite element method using the IIW-guideline „Fatigue design of welded joints and components“.