The high speed railway connecting Spain to France runs across the Municipality of Vilafant, some 25 km from the French border. To mitigate the barrier effect, two identical footbridges were built in 2011 over the railway, which runs 6 m below ground level.
The structures, which have a single span of 46 m, are built-in on both abutments, where the connection is monolithic. The 4.3 m wide clear deck consists of two outwardly inclined hybrid trusses. An innovative structural hybrid truss has been designed consisting of the combination of a stainless-steel Vierendeel truss with GFRP panels between vertical members. This creates an efficient, continuous structural web. The use of unusual geometric shapes fabricated using stainless-steel and GFRP are blended in an innovative fashion, giving rise to an austere and elegant solution.
Design/Construction ApproachThe geometry of the truss follows the structural demands from the integral frame configuration, having a variable height between 3.4 m at the abutment and 1.2 m at mid-span. The deck is built using slim GFRP ribbed panel planks over the transverse floor beams. Two different floor beams are alternated every 1.02 meters: I-GFRP 300 x 150 x 15 mm for lightness and stainless-steel rectangular 350 x 300 mm beams for rigidity. The GFRP panels between vertical elements in the Vierendeel trusses consist of a sandwich of two ribbed elements glued together for a total of an 80 mm thick translucent wall. The GFRP panels are continuously connected to both chords with stainless-steel bolts. In order to test the structural behavior and strength capacity of GFRP panels used as shear elements in hybrid truss configurations, several test models were designed and tested at the Institute of Building Sciences Eduardo Torroja (IETcc).