Seismic performance of intermediate moment frames with RBS-B connections

Abstract

The connections of special moment frames (SMF) should have a drift capacity greater than 4%, which is the minimum drift angle required by ANSI/AISC 358-05 for SMF connections. Since some reduced beam section with a bolted web (RBS-B) connection specimens failed to achieve 4% total rotation capacity, RBS-B connection is permitted for use only in Intermediate Moment Frames (IMF) according to the ANSI/AISC 358-05. In previous studies, some RBS-B connections could experience brittle connection fracture during earthquakes, which can also be detrimental to the seismic performance of IMF systems with RBS-B connections. The purpose of this study is to investigate whether IMFs with RBS-B connections provide a satisfactory seismic performance. The seismic performance of IMFs with pre-qualified RBS-B connections is evaluated based on the ATC-63 procedure. It is found that several IMFs with RBS-B connections do not satisfy the acceptance criteria specified in ATC 63.