Bridges that may have collapsed according to Codes

Three striking examples in bridge design, concerning concrete fatigue, concrete arch stability and connectors in composite construction, are in conflict with Eurocode provisions. A vast series of real structures can be found, for which such contradictions exist. Fatigue resistance of precast prestressed concrete bridge beams has been verified for 12 road and railway bridges and fails in half of these cases, although no sign whatever of deterioration has been found after 20 years. The reason for this is the extremely conservative value of concrete fatigue resistance, appearing in the code. Second-order effects and buckling of concrete arch bridges, including nonlinear material and structural effects, applied to heritage structures, demonstrates that the notion of slenderness, as used in the code, is rather inadequate. In addition, block connectors, frequently used in the past in composite construction, are now in opposition to the requirement of resisting an uplift force perpendicular to the steel beam. This calls for allowing larger freedom of designers and the reduction of the compulsory character of some clauses in codes.