Tremblay, Robert

Canadian Provisions for the Seismic Design of Single-Storey Steel Buildings With Flexible Roof Diaphragms

Abstract eng:
The seismic design provisions of the 2015 National Building Code of Canada (NBCC) for single-storey steel buildings with flexible metal roof deck diaphragms are presented. The 2015 NBCC provisions include a new expression for the fundamental period of vibration of buildings used to determine the minimum seismic design loads. The new period equation accounts for the flexibility of both the vertical bracing and roof diaphragm components. The NBCC also requires that the inelastic deformation demand on the vertical bracing elements be evaluated with consideration of the diaphragm in-plane flexibility effects. If needed, the design must be corrected to keep the anticipated deformations within the system deformation capacities. Magnification of roof diaphragm in-plane shears and moments due to diaphragm flexibility must also be taken into account for the design of the diaphragm. The new provisions are applied to a prototype single-storey building. Concentrically braced frames (CBFs) of the moderately ductile category are used and two bracing systems are examined: tension/compression and tension/only bracing. In addition, the building is assumed to be located at two different sites in eastern and western regions of Canada to account for the differences in seismic hazard. The buildings are assumed to be constructed on firm ground sites. In design, diaphragm shears and moments were predicted using a modified response spectrum analysis method. The design is found to significantly influenced by the seismicity level at the site and the bracing system used, which resulted in various properties and overstrength levels among the structures studied. The seismic response of the structures was examined though nonlinear response history analysis. The analyses showed that diaphragm flexibility effects on braced frame deformations were not pronounced for the structures studied. Diaphragm shears and moments can be well predicted using the proposed method.

Contributors:

Rogers, Colin

Conference Title:

Proceedings of the 16th World Conference on Earthquake Engineering

Conference Title:

16th World Conference on Earthquake Engineering

Conference Venue:

Santiago (CL)

Conference Dates:

2017-01-09 / 2017-01-13

Rights:

Text je chráněný podle autorského zákona č. 121/2000 Sb.