Modélisation parasismique des structures en béton armé.

Abstract

The necessity for faster methods that would ensure a reliable structural assessment or design of structures subjected to seismic loading led to the pushover analysis. Pushover analysis is based on the assumption that structures oscillate predominantly in the first mode or in the lower modes of vibration during a seismic event. This leads to a reduction of the multi-degree-of-freedom, MDOF system, to an equivalent single-degreeof- freedom, ESDOF system, with properties predicted by a nonlinear static analysis of the MDOF system. The seismic demands calculated for the ESDOF system are transformed through modal relationships to the seismic demands of the MDOF system. In this study the pushover method utilized as an alternative mean to general design and assessment. A modal analysis is initially carried out in order to reach the modes of the structure. The following stage consists to determine and reproduce the total behavior of the structure by the pushover analysis. Among several methods of analysis pushover, the method of capacity spectrum was selected; the results of this study prove that the safety margin opposite collapse is improved. By the addition of the walls, the demand curve tends to intersect the capacity curve close to the elastic range, which gives sufficient reserves of resistance and displacement. The walls were modeled by two methods; the study enabled us to judge that the method of equivalent gantry provided a reliable prediction of the behavior of the structures.