1. Introduction
Columns are structural elements which mainly transfer axial
loading to the foundation mainly originating from a building’s
self-weight and live loads, thus subjecting the structural
members of a building to nominal as well as transverse
shear forces. External forces such as earthquakes that lead
to local and overall buckling effects can be mitigated by the
structural columns. This is achieved through possession of
high capacity of resistance, making it a deterrent to
deformability. Normally composite columns are preferred in
the construction of high-rise buildings and other forms of
infrastructure.
COMPARISON AND ASSESSMENT OF COMPRESSIVE CAPACITY
OF HOLLOW AND CONCRETE-FILLED COLUMNS
Brian Otieno
School of Engineering, Design and Technology
Column Section
Discussion
Conclusion
Fig 1: Hollow Tube Column
Fig 2: Concrete-filled Tube Column
The data analysis provided by Eurocode 4 and SAP2000
reflect the influence of strength and structural shape of
composite columns experiencing uniaxial load.
In EC4 design code, the graphical analysis provides the
following evidence for both hollow and concrete-filled tube
columns:
• The area of cross-section is directly proportional to load
plastic resistance .
SAP2000 design method highlights the following
variables:
• Maximum resultant force, Fmax is more in hollow tube
sections than concrete-filled in circular and square
columns.
• The bending moment distribution, Mmax on column
sections is less in concrete-filled than hollow tubes.
• Shear forces generated are less in concrete-filled as
opposed to hollow tube of circular and square
composite columns.
The plastic resistance to uniaxial load is enhanced as the
steel grade increases. In both design methods filling of
concrete in between the steel shell boosts the strength of
the columns. This is due to the high compressive capacity
possessed by concrete.
Analysis based on EC4 reveals a greater uniaxial capacity
of rectangular hollow tube column than circular but vice
versa when filled with concrete. For SAP2000 the resultant
magnitudes derived from rectangular section are not
stable, however, show less resistance to uniaxial load than
circular section of both column states. This is assumed to
reflect the same effect on square section column due to
bearing a similar polygonal shape to the rectangular form.
In the final outcome both hollow and concrete-filled square
column had the highest uniaxial capacity in the two
methods of design.