ABSTRACT
Completing a structure starts with an appropriate design, based on structural requirements. The fundamental theories behind structural behaviour are well known and can be translated into sound mathematical language. Dimensioning the structure can finally be based on the concept of allowable stress levels or on the definition of safety factors relative to the failure condition of the structural element. Although design engineers are well acquainted with these concepts, due to the complexity of the structure, often in combination with uncertainties regarding the external loading, things can go wrong. Fortunately, structural failure does not happen very often, making engineering structures highly ranked within the list of most reliable man-made objects. In 1991, the Melle Bridge, Belgium suddenly collapsed while loaded by one truck. A design detail indirectly caused the collapse of the bridge. Unfortunately, the bridge seemed not very robust.
