Design and development
The development of the Von Mises, Monocontentio and Bicontentio prototypes consists of applying a particular design philosophy used by Mario Guisasola in multiple pedestrian bridges that can now be systematically implemented by other professionals.
Mario Guisasola’s design philosophy, synthesized in his doctoral thesis ‘Development of New Parametrized Shapes for Efficient and Elegant Footbridges’ is built on five basic fundamentals: integration in the geometry of the terrain, permanent search for simplicity, silhouettes that emerge from the structural behavior, unitary shapes and enduring details.
Systematization and parametrization
The systematization of the footbridge design aims to save time and engineering costs without necessarily having to rely on simplistic solutions.
Parametrization is linked to systematization and it allows to quickly and accurately particularize a design for a specific case.
Structural efficiency is obtained by using shapes that emerge from the beam’s structural behavior, implementing the graphs that interpret such behavior as structural silhouettes.
An elevation that is based on the bending stress diagram enables to optimize steel, using reduced depth sections at minimum bending stress zones. At the most loaded zones, the stress value remains constant in wide steel plate surfaces. As a result, very dynamic and sleek elevations with a great sense of slenderness are achieved.
The topography of the site determines the bridge and defines its structure. A vertical wall translates into a simple support and a slope into a fixed end. The embedding is achieved by means of an ancillary span that merges with the slope.
Once the structure is defined, its bending stress diagram determines its silhouette.
The typology implemented for all prototypes corresponds to a twin-girder steel bridge composed of two main box girders.
The main girders may be simply supported, fixed at one of the abutments or at both ends.
Basic structural components
The typology implemented for all prototypes corresponds to a twin-girder steel bridge composed of two main box girders connected by transverse floor beams on which a deck slab that will serve as the support of the pavement is concreted. Main girders can rest on two, three of four support axes, depending on whether the bridge is Von Mises, Monocontentio or Bicontentio.
The embedding is set by providing each abutment two support axes: one under compression and the other under tension. The support under tension corresponds to a double bolt joint that restraints vertical movements and allows horizontal movements. These geometrically basic elements are located inside abutments and are designed to remain hidden in the terrain.
The Von Mises, Monocontentio and Bicontentio prototypes have undergone an in-depth structural analysis that enabled to verify their structural efficiency and good dynamic behavior, achieving the maximum comfort degree, both for vertical and lateral vibration modes.