Performance Evaluation of Low-Disturbance Seismic Retrofit Method for Steel Column Bases Using Curved Member

Seismic retrofit techniques have always been an important subject in recent years for existing and new buildings. In addition, emergency (rapid) retrofit for damaged buildings right after a seismic event is also critical to ensure adequate capacities of the damaged buildings to withstand possible upcoming aftershocks. This paper first presents an introduction to a low-disturbance seismic retrofit method for steel column bases using curved members and its design approach. A case study of adopting the appropriate repair/retrofit method including a simple repair of the re-tightening process of anchor rods and a curved member retrofit system to the damaged building was performed. To evaluate the seismic performance of the structures, numerical models of four-story steel moment resisting frame buildings were developed and a series of analyses was conducted. The results show that the simple repair method could rapidly revert the overall stiffness of column bases subjected to a DBE-level earthquake while ensuring that the anchor rods have sufficient deformation capacity. The curved member retrofit system adopted in the analyses has proven that it can limit the structural responses caused by an MCE-level earthquake and reduce the seismic demand of the damaged column bases.