When establishing the market for studies on the execution of the work, the Contracting Authority specified in the contractual documents the spectrum of seismic response to be used. With this spectrum, the design offices carried out the seismic design of the structure on the basis of spectral modal analyzes while retaining a totally elastic behaviour of it.

The expertise carried out on the seismic hypotheses retained for the execution studies made it possible to highlight the strong underestimation of the elastic spectrum used for the calculations compared to the elastic spectrum defined according to EN 1998-5.

As part of the seismic expertise of the Moulay El Hassan II bridge, this report presents a seismic diagnosis of the structure by using post-elastic behaviours implying damage to the structure during the earthquake but guaranteeing the non-collapse.

The diagnosis of the structure was drawn up on the basis of the following analyzes:

  • analysis of constructional arrangements in areas of plastic ball joints,
  • evaluation of seismic efforts with taking into account a behavior coefficient,
  • acceptability of movements in terms of support.