Multimode pushover analysis for asymmetric buildings under biaxial seismic excitation based on a new concept of the equivalent single degree of freedom system

In this paper a new multimode pushover procedure is presented in order to achieve an approximate estimation of structural performance of asymmetric buildings under biaxial seismic excitation. The steps of the proposed methodology are quite similar to those of the well-known Modal Pushover Analysis. However, the establishment of the equivalent single-degree-of-freedom (E-SDOF) systems is based on a new concept, in order to take into account multidirectional seismic effects. The proposed methodology does not require independent analysis in each direction and the application of simplified superposition formulas for the combination of the horizontal seismic components is avoided. In addition, a reduction of the computational cost in relevance to other multimode procedures is achieved. After a brief outline of the theoretical background, a representative numerical example is given. Finally, the accuracy of the proposed methodology is evaluated by an extensive parametric study, which shows that, in general, it provides a useful design tool.

► A multimode pushover procedure is presented.
► It applies for the common case of asymmetric buildings under biaxial seismic excitation.
► It does not require independent analysis for each direction of excitation.
► A numerical example is given in order to facilitate comprehension.
► An evaluation study demonstrates the validity and the accuracy of the proposed methodology.