Importance of modal cross-correlations on wind loaded structures

in Proceedings of the 3rd International Conference on Bridge Maintenance, Safety and Management (2006)

In civil engineering applications the dynamic analysis of large structure is often performed in a modal space. This method is known to offer an interesting decrease of the number of degrees of freedom as ... [more ▼]

In civil engineering applications the dynamic analysis of large structure is often performed in a modal space. This method is known to offer an interesting decrease of the number of degrees of freedom as well as a decomposition of the structure’s response in “uncoupled” components. Even if the response in each mode can be computed independently from the responses in the other ones, in the context of stochastic loading, the coherence of these modal responses must be accounted for in the determination of the structural response. These quantities are known as the modal cross-correlations. In this paper we will show that these crosscorrelations can be important (contrarily to what is sometimes thought) even in case of wellseparated natural frequencies. This will be illustrated on the analysis of the famous Viaduct of Millau during an erection stage. [less ▲]

Effect of initial imperfections in numerical simulations of collapse behaviour of stiffened plates under compression

in Proceedings of the Third European Conference on Steel Structures (2002)

The slenderness of plated structures together with a generalised use of high strength steel leads to a great importance of stability phenomena. The practical way to deal with such problems is to use rules ... [more ▼]

The slenderness of plated structures together with a generalised use of high strength steel leads to a great importance of stability phenomena. The practical way to deal with such problems is to use rules proposed in design codes. A common alternative to design codes is the use of non linear finite element simulations. One of the most sensitive point in these simulations is the choice of the initial imperfections to be introduced in the model. The present paper discusses the effect of initial imperfections on the calculated collapse load. Several parameters are considered (shape, magnitude and direction). Results of numerical simulations are also compared with those of a design using Eurocode 3 or ECCS Recommendations. Two cases of plate geometry are studied (plate with one single stiffener and plate with multiple stiffeners). [less ▲]