The paper presents an experimental investigation on the structural performa
nce of cold formed steel members with bolted moment connections. Two lipped
C sections back-to-back with interconnections are used as beam and column
members. A number of connection configurations with gusset plates of both h
ot rolled steel and cold formed steel are proposed to form bolted moment co
nnections to accommodate members in practical orientations. Only the webs o
f lipped C sections are connected with bolts; the section flanges are not c
onnected for ease of construction. The structural performance of all the te
sts are presented in detail. Four modes of failure were identified among th
e tests:
BFcsw-bearing failure in section web around bolt hole
LTBgp-lateral torsional budding of gusset plate
FFcs-flexural failure of connected member, and
CBcol-combined compression and bending failure of column member.
It is shown that bearing failure is a ductile mode with large deformation c
apacity, and other failure modes may creep in to cause sudden collapse. Whi
le lateral torsional buckling of gusset plates causes pre-mature failure of
the connections at low applied load, flexural failure is more desirable as
over 80% of the moment capacity of the connected members may be safely mob
ilised at the connections. In the absence of effective torsional restraint
at the column ends, the column members may fail in combined compression and
bending. Among sixteen component and system tests, the moment resistance o
f bolted moment connections with four bolts per member was found to lie bet
ween 42% and 84% of the moment capacities of the connected members. Thus, i
t was demonstrated that moment connections among cold formed steel members
are structurally feasible and economical through rational design. (C) 1999
Elsevier Science Ltd. All rights reserved.