seismic design of bolted steel moment resisting frames


1.1. Introduction

Moment-resisting frames (MRFs) are structures that resist applied forces

primarily by bending of their members and connections. MRFs can provide large

open spaces without the obstruction usually caused by braces or shear walls. In

addition, because of their flexibility and relatively long period of vibration, MRFs

usually attract smaller seismic forces than the comparable braced or shear wall systems.





Since the early days of riveting, steel MRFs have been very popular in

building construction. Many structures including the monumental high-rises of

the late nineteen and early twentieth centuries have been built using riveted steel

MRFs. On the west coast, many turn-of-the-century tall buildings in San

Francisco have riveted steel MRFs. Since the 1960's, with the advent of highstrength

bolting as well as welding technologies, bolted steel moment-resisting

frames (BMRFs) and welded steel moment-resisting frames (WMRFs) have been

one of the main structural systems used in office and residential buildings.



In recent years because of ease of fabrication and design and for

economical reasons, most of the steel moment-res]sting frames used in seismic

areas such as California have had welded moment connections. However,

welded steel moment-resisting frames are only one of the many possibilities of

steel moment frames.



The main purpose of this report is to present information on the seismic

design of steel rigid moment-resisting frames with bolted or bolted/welded

connections. Today, there is sufficient information and experience that bolted

and bolted/welded steel moment-resisting frames can be designed and

fabricated to provide safe and economical structural systems for seismic regions.


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