Revision of ASCE 4

The original version of ASCE Standard 4, ``Seismic Analysis of Safety-Related Nuclear Structures`` was published in September 1986. It is ASCE policy to update its standards on a five year interval and the Working Group on Seismic Analysis of Safety Related Nuclear Structures was reconvened to formulate the revisions. The goal in updating the standard is to make sure that it is still relevant and that it incorporates the state of the practice in seismic engineering or, in some cases, where it has been demonstrated that state-of-the-art improvements need to be made to standard practice; new improvements are included. The contents of the new standard cover the same areas as the original version, with some additions. The contents are as follows: Input - response spectra and time histories; modeling of structures; analysis of structures; soil-structure interaction; input for subsystem analysis; special structures - buried pipes and conduits, earth-retaining walls, above-ground vertical tanks, raceways, and base-isolated structures; and an appendix providing seismic probabilistic risk assessment and margin assessment.