Vol 7, No 6 (2016) > Civil Engineering >

Development of Cold Formed Steel-Timber Composites for Roof Structures: Connection Systems

Ali Awaludin, Anindha Dyah Danastri, Bambang Supriyadi

 

Abstract: Cold formed
steel has relatively high width-to-thickness ratio elements, which causes it to
buckle easily. Combining it with timber laminas would be an effective solution
for reducing this buckling problem. This research focuses on the connection
system of a cold formed steel-timber composite, which was obtained
by attaching several timber laminas to the web part of cold formed
steel using screws. The connection used two bolts that were 8 mm in diameter,
as well as two different kinds of side plates: steel and plywood. Cold formed
steel 75Z08 and Swietenia mahagoni
(moisture content 12.2%; specific gravity 0.77) were used for connections and
were loaded in parallel and perpendicular directions. In addition, the
connections of cold formed steel (without timber laminas) using
self-drilling screw fasteners were tested until failure. Numerical analysis
predicting the load-slip curve and apparent yield load of the composite joints was
carried out using the DOWEL program and the European Yield Theory,
respectively. The test results showed that the connection system with steel
side plates is capable of accommodating the strength increase of composite
member, as it has a maximum load carrying capacity and initial slip modulus of
about 4.5 and 2 times larger than those of the cold formed steel connections, respectively. In the case
of a connection system with plywood side plates, its joint properties are
similar to those of the cold formed steel connection, except that it has larger
joint deformation.
Keywords: Bolted connections; Cold formed steel; Composite; Load carrying capacity; Timber laminas

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