COMPARISON OF RECENT US SEISMIC CODES

This paper compares National Earthquake Hazards Reduction Program (NEH RP), Structural Engineers Association of California (SEAOC), ASCE 7, a nd Uniform Building Code (UBC) seismic design provisions to address th e differences in their philosophies and applicabilities. These documen ts are compared by focusing on issues such as (1) purpose of earthquak e codes; (2) type of document and target audience; (3) lateral forces; and (4) analysis provisions. NEHRP and ASCE 7 documents are based on strength design while UBC and SEAOC are based on allowable or working stress design. There are other fundamental differences among these doc uments such as the required methods of analysis, building importance, detailing requirements, soil amplification factors, drift control and P-delta amplification, and the method of assigning an importance facto r. Several tables and graphs are presented to illustrate the similarit ies and differences among these codes.