Development of a design procedure for timber concrete composite ...

7. PROVISIONAL COMMENTS
The Gamma procedure is a robust and safe design
approach. However, there are several aspects of it that
are not yet fully understood. These parameters include:
• shear strength of the concrete notch – effect of the
coach screw,
• flexural shear strength of the beam – effect of deep
notch and use of the net area of the shear plane,
• short-term serviceability – initial deflection and
effect of concrete type and its curing,
• long-term deflection – identification of the creep
coefficient j 2 (global creep),
• distribution and spacing of the notch – understanding
of s min and s max .
A better understanding of these parameters may
contribute to the enhancement of the accuracy of the
design and the optimisation of TCC solutions. One of
these parameters, that is, the long-term deflection is
already under investigation at UTS. It is anticipated that
UTS will examine the other parameters in a near
future.
Further work will also focus on making the design
procedure more user-friendly wherever possible whilst
preserving the safety and functionality of the design.
8. CONCLUSION
Timber concrete composite (TCC) solutions have
generated a great deal of interest in Australia and New
Zealand over the last decade. This can be related to their
satisfying the ultimate and serviceability expectations
from modern architecture and design, which can help
them capture important markets such as medium rise
commercial and multi-storey residential buildings (up to
eight stories). TCC structures also represent a genuine
alternative to steel and concrete solutions.
TCC structures utilise the mechanical properties of
both materials even though the composite action is
only partial. As a result, they exhibit manifold
complexity. The design methodology presented in this
paper has adequately addressed the complexity of TCC
structures, including the partial composite action
provided by the connection, and imposes a
comprehensive series of strength checks on the crosssection
components, and serviceability checks with
consideration of the long term performance of the
structure.
The proposed design procedure is an adaptation from
the design procedure of EC5 and modifications have
been made to suit local practices. Adapting this
procedure to suit Australian practices has been a
challenging exercise and where assumptions have had
to be made due to uncertainties, these have erred on
being conservative. These assumptions are also areas
for further research in order to address the
uncertainties associated with them. The design
procedure thus reflects and capitalises on research and
development recently undertaken and in progress in
Australia and New Zealand.
9. REFERENCES
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14 NEW ZEALAND TIMBER DESIGN JOURNAL VOL 19· ISSUE 2