Comparison of seismic design for steel moment frames in Europe, the United States, Japan and China

Seismic provisions to guide the design of steel moment frames in Europe, the United States, Japan and China are comprehensively examined. Seismic hazard levels and performance requirements, ground type classification, magnitude and shape of elastic response spectra, seismic design force and distribution of required story shear strength, local ductility requirements, and reduction factors are compared. The results show that the no-collapse requirements in Eurocode and Japanese code correspond to a lower level of ground motion than the other two codes. The unreduced elastic response spectra given in four codes are quite different in recognition of different ground types and seismicity, in particular, Japanese code generally specifies much larger elastic spectrum than other codes. Although local ductility requirements are quite similar, U.S. code specifies higher reduction factors than Eurocode and Japanese code, while Chinese code stipulates a constant reduction factor with a relatively small value regardless of the ductility level of structures. As a result of such over-conservatism, Chinese code designed steel moment frames exhibit 20% to 150% larger lateral stiffness and resistance than Eurocode and U.S. code in most cases, while the significant even larger lateral stiffness and resistance predicted by Japanese code than that by Chinese code is mainly due to the larger seismic force from elastic response spectrum.