Proof‐of‐Concept Study of SMA‐Based Rocking Podium Structure Towards Mitigating the Soft‐Story Mechanism

ABSTRACT

The bottom story of modern buildings is often left as an open space to accommodate architectural functionality. However, this configuration tends to concentrate large deformations and severe damage in the bottom story under earthquakes, unintentionally forming a soft‐story mechanism. To this end, this paper proposes a shape memory alloy (SMA)‐based rocking podium structure, which employs a group of rocking columns at the bottom story to isolate the superstructure from experiencing significant damage while preserving the functional open space. The rocking columns are anchored to the foundation and podium using SMA bolts, which are adopted to enhance lateral resistance and dissipate seismic energy without impeding the recentering process. Gap openings are allowed to occur at column ends, forming rocking interfaces that can be closed with the aid of gravity and restoring force provided by SMA bolts. This study investigates the working mechanism of the proposed system and validates the concept through a 1/4‐scaled proof‐of‐concept test on an SMA‐based rocking column. A refined three‐dimensional solid‐element model is developed in ABAQUS to enable detailed local response observation. In addition, a multi‐spring model representing a three‐story SMA‐based rocking podium structure is established in OpenSees to evaluate its seismic performance at the structural level. Incremental dynamic analysis (IDA) is conducted under varying seismic intensity levels. For comparison, a three‐story moment‐resisting frame (MRF) is also developed in OpenSees.