Johnny Ching Ming HO and Dr Mianheng LAI
Thanks to the larger and
more continuous confining stress provided by hollow steel tube,
ultra-high-strength concrete-filled-steel-tube (UHSCFST) columns are advocated
rather than conventional transverse steel confined ultra-high-strength concrete
in tall buildings’ column design.
However, during elastic stage, de-bonding occurs as the Poisson’s ratio
of steel is larger than that of concrete, whereas in post-elastic stage,
confining stress, strength and ductility of concrete decrease as the steel tube
buckles. Thus, composite action between
steel and concrete cannot be fully developed.
To overcome this problem, external steel confinement in the form of tie
bars, rings and continuous spirals are proposed in this presentation to
increase the confinement effect of UHSCFST columns. A series of uni-axial compression test has
been conducted to study the behaviour of externally confined UHSCFST
columns. Results showed that the
proposed confining schemes can effectively improve the strength, elastic
stiffness and ductility of UHSCFST columns.
Moreover, rings and spirals are more effective than tie bars. Lastly, a theoretical stress-strain model was
used to predict the ultimate load and axial load-strain behaviour of the tested
columns, in which excellent agreement between the theoretical and experimental
results has been obtained. Results of
this pilot study are very instructive to the design of innovative composite
column and shear wall in the future.
About the Speaker:
Dr Johnny Ching Ming HO is a
Professor in the School of Civil Engineering, Guangzhou University PRC. Before joining the university in 2018, he
worked as a Senior Lecturer in the University of Queensland in 2013-2018 and an
Assistant Professor in The University of Hong Kong in 2007-2013. Practically, Dr Ho had about 5 years’ of
experience working in both Hong Kong and Brisbane offices of Arup on some large
scale infrastructure projects such as The Stonecutters Bridge in Hong Kong and the
Ipswich Motorway Upgrade (Wacol to Darra) in Brisbane. Dr Ho’s research interests are on mix design
of high-performance concrete with multi-sized fillers, rheology of cement paste
and mortar, as well as their application in concrete-filled-steel-tube columns.
Dr. Mianheng Lai is an Associate
Professor in the School of Civil Engineering, Guangzhou University PRC. Before, joining the university in 2018, he
worked as a Chief Project Manager in Country Garden Holdings from 2015 to 2018
in Zhaoqing and Foshan, Guangdong, China.
Dr. Lai received his PhD in 2015, supervised by Dr. Johnny Ho and Dr. HJ
Pam. Dr. Lai’s research interests are on
behavior of high-performance concrete-filled-steel-tube columns, seismic/fire behavior
of composite shear walls and concrete-steel-timber composite structures.
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