Seismic Design Forces for Ancillary Elements in Multi-storey Steel Framed Structures

This paper examines the seismic action effects considered in the design of ancillary elements attached to the floors of multi-storey structures. The current design procedures for non-structural elements in seismic codes are evaluated with particular focus on the provisions of Eurocode 8. The assessments are carried out through a detailed numerical investigation into the response of idealised ancillary elements incorporated within a large set of multi-storey steel frames of different heights and configurations. Nonlinear dynamic time history analyses are carried out on the frames using an extensive suite of ground motion excitations. The parameters considered in the numerical simulations include the structural configuration and associated properties, the ground motion characteristics, and the lateral strength demands on both the steel frames and the ancillary elements. The design forces induced within the ancillary components are determined based on the results of the numerical simulations and compared with the recommendations provided by Eurocode 8. It is shown that available code provisions exhibit several inadequacies, particularly in terms of capturing the influence of higher modes as well as in accounting for inelasticity effects in both the structural and non-structural systems. Based on the findings, modifications to current prediction approaches are proposed in order to improve the accuracy of the adopted design forces for ancillary elements.