Hot Rolled I Sections Seismic Category Classification

All steel members which form part of a seismic resisting frame are classified into one of 4 categories for the purpose of seismic design. Category 1 members are capable of sustaining high displacement ductility demands. Category 2 members are capable of sustaining low ductility demands. Category 3 members are capable of developing their nominal section capacity where required to in bending. Category 4 members need not be designed to sustain any displacement ductility demand. Limits are placed on member section geometry for the various categories and this is found in section 12.5 of the Steel Structures Standard (SNZ, 2007). Previous tables have been developed classifying I section members into the appropriate categories (Feeney, 1993). These tables were developed based on the 1992 version of the Steel Structures Standard . Hot rolled steel sections classified were grades 250 and 350. Welded sections classified were limited to WB and WC sections. This article updates the Member ductility category of I sections for seismic design tables for Grade 300 hot rolled sections in accordance with the latest Steel Structures Standard (SNZ, 2007).

MEM1001.pdf

Kevin Cowie; Alistair Fussell