Modular pedestrian bridge with concrete deck and IPC truss girder

The paper reports on the design, by means of analytical and numerical tools, the experimental verification of structural elements and the joining procedure of a 13 m span pedestrian bridge, which is composed of a concrete deck and three truss girders made of Inorganic Phosphate Cement (IPC) sandwich panels. The IPC is a cementitious matrix which does allow reinforcement with glass fibres. The bridge project wants to examine the feasibility of building structures with IPC, in view of the advantages of this material: low manufacturing cost, non-inflammable behaviour, chemical resistance and an environmentally friendly composition. The IPC sandwich panels that compose the truss girders, are connected by steel elements, which allow a rapid assembly by pin joints. The design is accompanied by experimental tests on bridge components. These tests reveal that the metal connections are the weak point of the bridge. This is due to assembly problems related to the manufacturing accuracy of both IPC sandwich panels and steel connection elements, and due to the uncertainties as to the connections of the steel inserts to the IPC skins of the sandwich panels. The design shows that in spite of the low stiffness of the glass fibre reinforced IPC, the use of IPC still leads to realistic dimensions of the bridge structure, and to the confirmation that sufficient strength can be obtained for structural applications. The main novelty of the project appears in the bridge concept, which is an act of composite thinking. The project applies classical methodologies for calculations, validation and prototype realization, but shows that a workable structure can be obtained by the synergetic combination of materials, with in this case the IPC as main component.