Influence of Foundation Flexibility on Seismic Behavior of Self-Centering RC Frames

The main aim of this study is to focus on the seismic behavior of a self-centering system considering the effects of foundation flexibility, i.e., soil–structure interaction (SSI), under near-field earthquake motions. The influence of soil flexibility on multistory SMA frames has generally been ignored. Therefore, the seismic behavior of RC moment frames with both traditional reinforcing steel and shape memory alloy is investigated through nonlinear dynamic time-history analyses considering soil–structure interaction. Four- and seven-story RC frames with SSI are designed, detailed and analyzed. For each structure, three different reinforcing steel profiles are considered: the first structure is configured with only regular/conventional steel reinforcement, the second structure is configured using SMA applied at the beams’ plastic hinge section and conventional reinforcement in other parts, and the last structure is configured with beams completely reinforced with SMA. In every case, a regular/conventional steel rebar is used in all columns. Nonlinear static pushover analyses are conducted to specify the lateral capacity of the considered frames. Eleven different earthquake records with near-field effects recorded on soft soils are selected for the nonlinear time-history analysis. Additionally, for steel-SMA and SMA structures, the fixed-base case, i.e., without soil–structure interaction, is also analyzed. The findings are utilized to assess how soil flexibility affects SMA frames and are limited to the considered frame type and soil conditions.