2011

Dynamic Testing of Low-Rise Steel Framed Buildings with Flexible Roof Deck Diaphragms
(In collaboration with Robert Tremblay, École Polytechnique, and Jean Proulx & Charles Philippe Lamarche, Université de Sherbrooke).
Steel structures are commonly used for single-storey buildings with large footprints, typically constructed with a roof diaphragm made of corrugated steel deck sheets. When subjected to lateral wind or seismic loads, the roof diaphragms experience in-plane shear and flexural deformations that are added to storey drifts caused by deformations of the vertical elements of the lateral load resisting system. This effect is generally accounted for in current design procedures. However, the in-plane flexibility of metal roof deck diaphragms may also result in longer building periods compared to those obtained assuming rigid diaphragm response and this effect is generally ignored when determining horizontal seismic design loads.

The objective of the proposed research is to validate, by means of measured building behaviour under ambient and forced dynamic loading, the current methods used to predict the fundamental period of vibration of low-rise CBF steel buildings with flexible roof deck diaphragms and to measure the effect of the roof diaphragm on the overall building response.

Two CBF structures located in the Montreal area will be instrumented and tested under a range of frequencies. Both ambient and forced vibrations will be measured. Damping characteristics will also be evaluated by pull-back tests. The scope of the research also includes modelling of the buildings using elastic models (SAP 2000) and inelastic models (OpenSees). The image above shows photographs of prototype test building with data acquisition, shaker and velocity transducers.

This research will lead to recommendations on the provisions of specific low-rise building seismic design for inclusion in the CSA S16 and NBCC.