DEVELOPMENT OF UNITED-STATES SEISMIC CODES

This paper aims to clarify for design engineers the basis on which seismic lateral loads are established in US codes. The particular empirical seismic response spectra recommended in the AISC seismic provisions will be discussed. Such curves give the base shear coefficients for various buildings as a function of their natural period. The relationships of seismic code provisions to the actual behavior of buildings during an earthquake is presented. A brief comparison of lateral load provisions in the US and those of Canada, Japan and Europe follows. For engineers unfamiliar with seismic design, the various technical terms used in earthquake engineering are introduced and defined.