Abstract
Double-bay or multi-bay portal frames of hot-rolled steel have been in existence since the
development of the plastic analysis theory, and the behaviour of the eaves connections of these
frames are well established. With the increasing use of cold-formed steel in portal frames, it is
necessary to develop connecting structural systems that are favourable to these elements, and
to understand the behaviour of these connections. The purpose of this investigation is to
develop internal eaves connections of double-bay portal frames of cold-formed steel channels,
with the main frames members connected back-to-back. In double-bay portal frames, the
columns of two single-bay portal frames, positioned adjacent to each other, are replaced by one
internal column. Two internal eaves connections were developed and investigated, and are
referred in this paper as Eaves Connection Type 1 (ECT-1) and Eaves Connection Type 2
(ECT-2). Tests were then performed to determine the capacity and failure mechanism of these
connections, including the members forming these connections. Although the failure
mechanisms included local buckling of the compression zone of the web and flange of the
channels, and bolt-bearing deformations, all frames finally failed by local buckling of the web
and flange of the channels. The moment-curvature graphs show that enough plasticity could
not be achieved in both connections.