Dynamics of rocking podium structures

• Published in: Earthquake engineering & structural dynamics 2017-11, Vol.46 (14), p.2499-2517
• Main Authors: Bachmann, J.A., Vassiliou, M.F., Stojadinović, B.
• Format: Article
• Language: English
• Subjects: Aseismic buildings; Columns (structural); design guidelines; Displacement; Dynamic models; Dynamics; Earthquake construction; Earthquakes; Forces (mechanics); Ground motion; Guidelines; in‐plane seismic response; Philosophy; Rigid-body dynamics; rocking structural systems; Seismic activity; Seismic analysis; Seismic design; Seismic response; Seismology; Spectra; Structures; Uplift
• ISSN: 0098-8847; 1096-9845
• DOI: 10.1002/eqe.2915

Summary A rocking podium structure is a class of structures consisting of a superstructure placed on top of a rigid slab supported by free‐standing columns. The free‐standing columns respond to sufficiently strong ground motion excitation by uplifting and rocking. Uplift works as a mechanical fuse that limits the forces transmitted to the superstructure, while rocking enables large lateral displacements. Such ‘soft‐story’ system runs counter to the modern seismic design philosophy but has been used to construct several hundred buildings in countries of the former USSR following Polyakov's rule‐of‐thumb guidelines: (i) that the superstructure behave as a rigid body and (ii) that the maximum lateral displacement of the rocking podium frame be estimated using elastic earthquake displacement response spectra. The objectives of this paper are to present a dynamic model for analysis of the in‐plane seismic response of rocking podium structures and to investigate if Polyakov's rule‐of‐thumb guidelines are adequate for the design of such structures. Examination of the rocking podium structure response to analytical pulse and recorded ground motion excitations shows that the rocking podium structures are stable and that Polyakov's rule‐of‐thumb guidelines produce generally conservative designs. Copyright © 2017 John Wiley & Sons, Ltd.