Abstract:
Hollow core fiber reinforced polymer concrete steel composite column is structural
element which have a concrete shell encased between fiber reinforced polymer tube on
the outer surface and steel tube in the inside surface. The column offers high strength to
weight ratio and good structural performance than solid reinforced column and superior
environmental resistance than steel tube encased hollow core columns.
This study had considered those variables that have effect on the behavior of the column
but are not studied in the past. It numerically investigates the structural behavior of the
column under combined axial and lateral loading. The column has circular cross-section
with the outer fiber tube truncated at the top of the footing while the inner steel tube is
embedded in the footing. Experimental result reported in the literature was used for
validating the finite element model analyzed using ANSYS nonlinear finite element
software program. The column was modeled as a cantilever column. Then, parametric
studies on influential variables such as the effect of embedding the FRP tube in the
footing, the effect of changing the configuration of the two tubes i.e. steel vs. FRP tubes,
the effect of tapering the thickness of the two tubes throughout the height o f the column
and the effect of steel tube yield strength was conducted to get insight in to the structural
performance of the column.
Finite element analysis results indicated application of both external and/or internal
surfaces with steel tubes and/or fiber reinforced polymer affected structural performance
of the column. The hollow core column having concrete shell encased between two steel
tubes showed 108% and 12% higher in initial stiffness and moment capacity than hollow
core column having concrete shell encased with fiber reinforced polymer from outside
and steel tube from inside. Decreasing the average thickness of both steel and FRP tubes
by 25% above the column-footing connection showed same moment capacity with the
column having uniform thickness. Additionally, increasing yield strength of the steel tube
from 310MPa to 586MPa raised the moment capacity of the column by 24.4%.
Keywords: Hollow core column, composite column, Finite element analysis, steel
encasing, FRP tube