Numerical study of the effect of Post-Liquefaction settlements on the response of infilled RC-frames

The liquefaction of soils is one of the most severe results of earthquakes. Indeed, post-liquefaction settlements are the main responsible for critical damages and collapse in shallow-founded buildings. The study of the behavior of buildings subjected to post-liquefaction settlements is rather complex since it requires to consider the interaction between the effects of ground shaking and the effects of liquefaction failure. In particular, large inelastic deformations occurring during severe earthquakes are responsible for residual permanent displacements which could particularly influence the response of structures with respect to post-liquefaction settlements. In this paper it is presented a simplified numerical approach finalized to assess the response of infilled reinforced concrete (RC) frames toward post-liquefaction settlements. Like to a previous approach presented by the Authors for bare RC-frames, the proposed approach is based on a procedure where the influence of seismic inelastic displacements on the effect of post-liquefaction settlements is evaluated throughout a set of static nonlinear analyses instead of more complex dynamic time-history analyses. Here, in addition, the Authors opportunely enrich the approach to account for the influence of the damage attained by the infill on both the seismic response and post-liquefaction settlements. After a preliminary discussion concerning some important aspects of the behavior of infilled RC-frames toward seismic events and post-liquefaction settlements, the proposed approach is presented in detail and applied to some cases of study deduced from literature. Additional numerical analyses are also performed in order to further underline the ability of the approach to account for the important role of infill panels on the seismic response and the subsequent activation of post-liquefaction settlements.