Dynamic Coefficients or Response Spectra of Structures to Earthquake?

Abstract

There are big differences in definition of the seismic input in the norms of the Russian Federation code and in the foreign countries standards. Almost all normative documents and guidelines for the earthquake resistance analysis of structures in technically developed countries of the world used the concept of the response spectra concept. In the norms of the former USSR and the Russian Federation to assess the seismic effects used and continues to use the concept of "spectral coefficient of dynamism" - β. We believe that the concept is erroneous. The use of bad and erroneous terms can not only complicate the understanding of the phenomenon, but also lead to wrong decisions. Such unsuccessful terms include the terms "dynamic coefficients" used in the norms of the Russian Federation in the calculation of seismic resistance. The displacements, velocities, or accelerations response spectra to earthquakes have a clear and understandable physical meaning. The response spectra can be represented in Codes in a standard site-independent form. Site-specific response spectra can be developed if the sites have some specific properties. For soft soil sites, characterized by soils having alow shear wave velocity or for facilities within 15 km of active faults. What are the "dynamic coefficients" for seismic effects is not clear. None of the codes of the Russian Federation (SP 14.13330.2018, SP 268.1325800.2016, etc.) does not provide a definition of the "dynamic coefficient" for seismic effects. It can be noted that in the monographs of Russian authors there are neither definitions of dynamic factors for earthquakes, nor methods for their developing. The concept of "dynamic coefficients" should be excluded from the normative documents, replacing them with response spectra.

Keywords

• seismic input, dynamic coefficient, response spectrum, foreign seismic standards, Russian code